Black Ghost Knife Fish 101: Care, Tank Mates, And More
- by Millie Sheppard
- Updated: April 27, 2022
- 112.3K views
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The black ghost knife fish is one of the most interesting and unique freshwater species that we’ve ever seen. When you see one in person you won’t forget it!
Because of their appearance, these fish have gotten a fair amount of attention from the aquarist community. But in our experience, there’s a lot of misinformation being passed around about this species.
Black ghost knife fish care is not as straightforward as a lot of other freshwater species. This is partly due to their size, but also unique conditions that these fish need.
This guide will teach you everything you need to know about owning these fish. By the time you’re done reading, you’ll know their recommended tank mates, food, diet, tank size, and much more!

Table of Contents
Water parameters, what to include in their tank, diseases to watch out for, recommended food & diet, behavior & temperament, black ghost knife fish tank mates & compatability, breeding information, what’s next, general species summary.
Black ghost knife fish ( Apteronotus albifrons ) are a tropical freshwater fish that have been steadily growing in popularity over the years. This is mostly due to their incredibly unique appearance that makes them stand out in any tank.
They get their name from two sources. The “black knife” portion comes from the obvious resemblance these fish have to a blade (especially if you think of the white rings on their tail as a handle). The “ghost” piece of their name originates from the local belief that ghosts of the dead occupy the bodies of these fish.
Black ghost knife fish come from a few areas in South America. The Paraná and Paraguay River are two bodies of water with a large concentration of these fish. If you follow these bodies of water they can be found in countries like Paraguay, Argentina, Venezuela, and Brazil (among others).
One interesting fact about this species that many people don’t know is that they’re electric. They’re not capable of stunning you or anything like that, but they use electric receptors to help them locate hard to find food.
Since they’re nocturnal and do most of their hunting at night, this is obviously quite a useful skill to have!
The average lifespan of a black ghost knife fish is around 10 years under solid care conditions. However, this can reach up to 15 years in some cases!
The main factors that influence their lifespan are the quality of overall care (both before you purchased your fish and after) as well as genetics. Do the best you can with the factors you can control, and you’ll likely have this fish for quite a while.
This is where things get fun.
The appearance of the black ghost knife fish is obviously the main reason why these fish are so popular. There’s really nothing like it!

Their bodies are long, thin, and slightly curved (like a knife). The vertical width of this fish tapers off gradually before thinning out significantly at their tail.
They don’t have a dorsal or caudal fin. On the top of their body, there’s simply a thin ridge. Their tail (where you would expect to see a caudal fin on other fish) is very skinny with a couple of spaced out white bands.
Since they don’t have a caudal fin, the black ghost knife fish generates momentum from their pectoral and anal fins. This gives them a beautiful, flowing swimming style.
One way to describe how they use their anal fin to move would be by comparing it to the wings of a stingray. There’s a wave-like effect that gives them an impressive amount of mobility.
Their pectoral fins are average-sized with a wide surface area. Because of their unique body tyle, they rely on their pectoral fins quite a bit to get around.
When it comes to coloration, there’s really not much to talk about. Other than the two white bands/rings on their tail, these fish are almost completely black. The ridge that starts at their head and runs across their entire back is sometimes a bit lighter in color, but that can vary.
The average black ghost knife fish size is somewhere between 18 and 20 inches when fully grown. This is one of the most commonly misunderstood pieces of information about this species. A lot of potential owners seem to think they’re a lot smaller than they really are!
Author Note: Don’t fall victim to the “they will grow to fit the size of their tank” school of thought that’s floating around in forums online. These fish will grow to be quite large no matter what tank size they’re in.
Black Ghost Knife Fish Care
Due to their size, unique body type, and disease sensitivity, this species is not a great fit for beginners. Black ghost knife fish care is something that’s a better fit for an aquarist who’s been around the block a few times.
This section will break down the key aspects of care when it comes to tank and water needs. Read it carefully to decide if owning these fish is right for you.
The minimum tank size for one black ghost knife fish is 100 gallons. These fish can grow to be quite large and need a tank that’s big enough to accommodate them.
Keeping a fish of this size in a smaller tank will not only increase their aggression, but it will cause their health to suffer as well. Having the right tank size serves as the foundation that all other care factors are built on.
You could have the best water quality in the world, but if the tank is too small it ultimately won’t matter.
If you want to keep multiple black ghost knife fish in the same tank you’ll need to increase the tank size. Aim for an additional 80-100 gallons per extra fish you add. This will minimize the chances of them showing aggressive territorial behavior toward one another.
The baseline water parameter ranges that these fish can handle are actually rather flexible. This is because their natural habitat is anything but clean (hence their need to use electricity when finding food).
- Water temperature: 73°F to 80°F
- pH levels: 6.5 to 8
- Water hardness: 0 to 10 KH
But even though the parameter windows are fairly flexible, these fish are actually quite sensitive to suboptimal water conditions. They are not like other hardy species that can tolerate average water quality (even though you should never settle for it).
This means you need to take water quality very seriously if you own a black ghost knife fish. They can easily get sick (more on that later) and as you probably know, the chance for disease in a tank with poor water is always high.
The same thing goes for shifts in water parameters as well. It’s important to keep levels as stable as possible with this species. If you see a shift starting to occur it’s on you to nip it in the bud.
Author Note: Since water parameters and general quality are so important when it comes to black knife ghost fish care, you should invest in a solid water test kit. An inaccurate kit is just as bad (or worse) than no kit at all. Make sure the levels and readings you’re getting back are accurate so you can make informed decisions about how to treat the water in your aquarium.
When it comes to setting up the perfect tank for these fish, you’ll want to use their natural habitat as a reference.
In the rivers they come from, black ghost knife fish are regularly navigating various objects to hide or look for food. Trees, logs, rocks, and plants are in abundance.
This means you should try to bring some of that into their tank. This is where having the adequate tank size (or something a little larger than the minimum) comes in handy. You’ll be able to furnish the aquarium with plenty of features without it impacting their room to swim.
Before you add anything it’s important to use a soft substrate. These are bottom-feeder fish which means they’ll be spending a lot of time in the lower portion of your tank.
Fine sand or gravel is best, although we have some people get away with slightly larger gravel too (not our preference though).
The reason why a soft substrate is important for these fish is their body type. Black ghost knife fish have fairly fragile skin and no scales. This means a coarse substrate could cut them and potentially lead to an infection or illness.
Once you’ve settled on your substrate it’s time to add some hiding places.
Black ghost knife fish aren’t picky when it comes to hiding places. Any of the typical aquarium plants , rocks, driftwood, or caves will be fine.
We recommend a mixture of all of these if you have enough space. This is where you can start to get creative with how you want to set things up based on personal preference. Plants are the most important, so always try to include a few no matter what layout you decide on.
Author Note: It’s important to avoid any hiding places or objects that have rough surfaces. This means smooth rocks, caves, and driftwood. You don’t want these fish to get cut!
Because of their makeup, black ghost knife fish are more likely to get skin diseases than other species. This is because they don’t have the scaley armor that other fish can rely on.
Just like it is with most freshwater fish, Ich is always a disease to watch out for. This will show up as white spots on their skin (which will be easy to spot due to their black color) and you’ll likely notice a change in their behavior as well.
If they get cut or scratched this can also increase the possibility that they’ll get an infection. It’s important to monitor any cuts you see to make sure they’re healing properly. If the cut doesn’t appear to be making any progress you’ll need to look into treatment options.

This is why it’s so important to spend a few minutes each day inspecting your black ghost. Too often owners get into the habit of treating their aquarium like background imagery and don’t take a closer look.
Any physical or behavioral symptoms that look out of the ordinary should be taken seriously with this species. Time is of the essence.
Author Note: Investing in a great filter like the Fluval FX4 and a UV sterilizer are effective ways to reduce the chance of this fish getting sick.
The ideal diet for black ghost knife fish is very similar to what they eat in their natural habitat. Unlike some other species, these fish tend to be very resistant to transitioning over to flake or pellet foods.
Because of this, we prefer to give them what they want. From what we’ve observed, the black ghost knife fish that have lived the longest have been fed with a more protein-rich and natural diet.
Any of the go-to live or frozen foods will work (a variety is always recommended). Bloodworms , prawns, brine shrimp, and tubifex are used by owners regularly.
Since these fish are nocturnal you’ll need to work around their sleep cycle. The easiest way to do this is by feeding them once a day, and doing it in the evening or night (depending on your schedule).
Early on in your ownership, it’s crucial to make sure you’re not overfeeding them. If they can’t eat all the food you gave them in a couple of minutes, reduce the quantity.
Overfeeding will not only impact their health directly (fat fish are sick fish), but it will result in extra waste in their water. If you read our water quality section you’ll know how dangerous that can be to this species.
In general, black ghost knife fish want to mind their own business. They’re relatively active fish that prefer to do their own thing and be left alone.
They’re used to swimming in and out of hiding places near the substrate looking for food. Anything else is extra stress they don’t want to deal with!
However, they have an aggressive side.
This will pretty much only present itself when they’re around other black ghost knife fish. But don’t worry, it doesn’t mean you can’t keep two or more in the same tank.
As long as these fish have enough space to call their own, it’s unlikely that they’ll be aggressive toward one another. It’s just when two or more are crammed into close quarters that they can get pretty grumpy (which we understand).
There are a number of compatible black ghost knife fish tank mates you can consider. This is because this species likes to mind their own business and doesn’t use its size to be a bully.
Almost any peaceful freshwater fish can be paired with your black ghost as long as they’re not too small. Some owners have gotten away with small fish like Celestial Pearl Danios or Green Neon Tetras but that pairing tends to only be viable while the knife fish is still on the small side.
Here are some black ghost knife fish tank mates we recommend:
- Electric Blue Acara
- Silver Dollar Fish
- Oscar Fish (this pairing needs plenty of space)
- Cory Catfish
There are tons of other tank mates you can try, but those are a good starting point.
Author Note: If you want to keep multiple black ghost knife fish in the same tank you need to make sure they have enough space. Also, we recommend capping the number at two per tank. Any more than this will significantly increase the potential for aggression no matter how big your tank is. This is because they have bad eyesight and will probably bump into each other when looking for food!
Breeding these fish is something we don’t recommend due to the lack of information that’s available on the process. There are so many conflicting methods that have been tried that it’s hard to tell what works and what doesn’t.
Unlike some of the other guides on the internet that are fine passing along general best practices and hoping for the best, we believe it’s be a disservice to these fish to encourage owners to breed them without a reliable course of action.
In the future, if more breeding information becomes available we’ll gladly add it to this guide. Until then we don’t encourage anyone to try it in a home aquarium.
Black ghost knife fish care is a very rewarding process if you’re up to the challenge. It never gets old watching these fish swim around the aquarium!
Now that you have a better understanding of what kind of effort is required if you want to own this species, it’s time for you to decide if they’re right for you.
We always encourage potential owners to be as honest with themselves as possible when doing this. The worst thing you can do is purchase a fish you’re not prepared to care for (it’s not good for anyone).
If you’re on the fence and have any questions about black ghost knife fish let us know. It’s our mission to encourage and help as many informed aquarists as possible!
Millie Sheppard
As an avid Aquarist, Marine Biologist, and PADI Diver, Millie is dedicated to exploring and preserving the wonders of our oceans. She is looking forward to create a career in the field of aquatic ecosystems based on a deep-rooted love for marine life and a commitment to environmental conservation. She is always eager to connect with fellow marine enthusiasts, scientists, conservationists, and publications seeking engaging marine-related content. Feel free to reach out to Millie to: [email protected]
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Researchers refer to a number of different types of fish as “Knifefish.” You can find several different families of fish by this name in the taxonomic order Gymnotiformes.
Additionally, several other unrelated species go by the same name. However, for our purposes this article will focus on the popular aquarium pet, the ghost Knifefish. Read on to learn about the Knifefish .

Description of the Knifefish
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Researchers recognize a large number of different species, and each is slightly different from the next. However, they all share a similarly odd body shape. Their bodies have an elongated and somewhat eel-like shape. Like eels, their dorsal and tail fins also form one ribbon-like structure.
Unlike eels, their body shape isn’t uniformly tapered. They have a rather knife-like shape, with the tail tapering to a point and the midsection or abdomen flaring outward drastically. While the popular aquarium varieties measure about six or seven inches, some species reach up to two feet in length.
Interesting Facts About the Knifefish
With such a wide variety of these odd fish, you can find many interesting traits, adaptations, and shapes. Learn more about some specific species, below.
- Black Ghost Knifefish – This species is one of the more popular with home aquariums. As their name suggests, this species look somewhat like a black ghost. Their entire body is black in color, with several bands of white on their tails. The undulating motion of their fins enhance this effect.
- Tamandua Knifefish – This species lives in the Amazon river and its tributaries. It has light pink or white colored skin and an abnormally long rostrum, or snout. That snout is how it got its name, as it resembles the mouth of the tamandua anteater .
- Sternarchorhynchus – Researchers recognize 32 species in this odd genus. Members of this group feature an abnormally extended and downturned rostrum. It gives them an appearance similar to that of an elephant’s trunk. Many species face severe habitat destruction .
Habitat of the Knifefish
Though habitat choice depends on the species at hand, many in this group have similar preferences. They often utilize fast-moving waters, like creeks and streams.
Many species also prefer deeper waters with little light penetration. Those that live in deep rivers live below 16 ft. or more. You can often find them near the bottom of the river or stream that they occupy.
Distribution of the Knifefish
You can find the various species throughout freshwater habitats in Central and South America. While some species live across larger ranges, most live only in a small region.
Each species has its own unique range, and the populations of some species occasionally overlap with other species. The majority of these fish live within the Amazon River Basin.
Diet of the Knifefish
Diet changes based on the size of the fish and where they live. The vast majority of species have carnivorous feeding habits, though they typically prey on invertebrates. However, at least one species is herbivorous and eats sponges.
Some examples of typical prey for most species include small fish, fish eggs, shrimp, zooplankton, insects, insect larvae, small crustaceans, and more.
Knifefish and Human Interaction
Human activity threatens each species differently. Some have healthy population levels and do not face the same level of decline as other species. In threatened species, such as the Chitala chitala , also known as the Indian Featherback Knifefish, habitat destruction and degradation pose the greatest danger.
Climate change also impacts their invertebrate prey species, and thus impacts them. For many species, researchers simply do not have enough data to properly designate a threat level.
Domestication
Humans have not domesticated these fish in any way.
Does the Knifefish Make a Good Pet
Some species do make good pets. However, you should never purchase a wild-caught pet. When people purchase wild-caught animals it can spread disease to their other fish, or deplete wild populations.
Knifefish Care
The most popular pet species is the Black Ghost. You can commonly find this species in home aquariums. They need tanks of at least 100 gallons, as adults can reach lengths of about 20 in. or so.
Though they easily live in tanks with other peaceful fish species, they are not social, and you should not keep them with other Black Ghosts. You should feed frozen brine shrimp or bloodworms, though some eventually eat standard fish food.
Behavior of the Knifefish
Each species has its own unique behavior. However, many within this group live nocturnal lives. This means that they hide during the day and hunt for food at night.
All species have poor eyesight, but they use a unique electromagnetic field to “see” the electrical fields of the creatures around them. Because of this, they can live in dark, deep waters and still hunt effectively.
Reproduction of the Knifefish
Each species has its own unique reproductive rates. In fact, for many species, researchers know little to nothing about their breeding habits. Different species have different courtship rituals, egg production, and hatching time. It also takes varying amounts of time for the young to reach sexual maturity.
Beliefs, Superstitions, and Phobias About the Knifefish
Some native Amazonian tribes believe that, when a family member passes away, their spirit goes to live in the body of the Black Ghost fish.
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The Name That Fits
Knifefish are some of the most interesting freshwater aquarium fish available. Their unique "knife blade" body shape and ability to swim backwards using their undulating bottom fin make them fascinating additions to appropriate aquarium communities. Knifefish can be placed in two main groups: The largest group belongs to the Order Gymnotiformes and are found in Central and South America. They include ghost knives, banded knives and glass knives. A smaller group, in the Family Notopteridae, are native to Southeast Asia and Africa and include featherfin, African and clown knives. Most knifefish have the ability to generate and receive electrical discharges, which they use for navigation, communication and locating prey. Knifefish are not for beginner aquarists due to their specialized feeding requirements and in some cases, large adult size.
Natural Habitat for Knifefish
Knifefish occupy a variety of habitats in the wild, including lakes and large rivers. Several species move into flooded forests during the wet season to breed. While most species inhabit quiet water with abundant vegetation, glass knives prefer deep river channels with strong currents. Most species are exclusively freshwater, however, a few knifefish, such as the featherfin, spend brief periods in brackish water.
Knifefish Water Requirements
Knifefish are scaleless and extremely sensitive to poor water conditions. Water quality should be pristine, with undetectable ammonia and nitrites, and nitrates below 20 ppm. pH should be between 7.0 and 8.0, with alkalinity between 5° and 10° (90 ppm to 180 ppm). Temperature should be maintained between 75° and 80° F. If the aquarium is kept in rooms below 75°, use an Aqueon Aquarium Heater to maintain the correct temperature. Knifefish are sensitive to many medications, so the use of a UV sterilizer is recommended to prevent disease rather than having to resort to chemicals after a disease outbreak. Maintain good filtration and change 10% of the water every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner . Do not forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Housing Requirements for Knifefish
Since some knifefish grow to be relatively large and most live long lives, appropriate plans should be made when purchasing them. Ghost knives, featherfin knives and African knives attain lengths of 8" to 12", requiring an aquarium of at least 55 gallons when full grown. Banded knives require at least 100 gallons and adult clown knives will require a 200-gallon aquarium or larger. Aba Aba knives reach lengths of over 5' in the wild and are not suitable for home aquarists. Plenty of cover in the form of tall plants and driftwood, as well as caves and grottos, should be provided to help knifefish feel safe. Ample open areas for swimming should also be present. Ghost knives are well suited to live in planted aquariums due to their calm, peaceful nature. When keeping large knives, use artificial plants with weighted bases to prevent them from being uprooted. Lighting should be subdued to encourage them to come out during the day and a secure cover should be used to keep them from jumping out of the aquarium.
Knifefish Behavior/Compatibility
Most knifefish are nocturnal and tend to be shy, especially when first introduced to an aquarium. As they settle into their new homes, they often become more outgoing during daylight hours, particularly around feeding time. They tend to be territorial and can be aggressive toward each other or closely related species, so they are best kept one to an aquarium with other peaceful fish that are too large to be eaten. This is especially important with clown knives, which not only get extremely large, but are highly predatory. Depending on the species of knifefish you keep, a few compatible fish include silver dollars, tinfoil barbs, angelfish, large cichlids, larger Gouramis and Synodontis catfish. Always consult an aquarium expert before buying any new fish for your aquarium.
What Do Knifefish Eat?
The majority of knifefish are specialized feeders, with a number of species foraging the bottom at night in search of crustaceans, worms, insects and small fish. Clown knives, African knives and featherfin knives are active predators and will eagerly swallow any fish they can fit in their mouth! It is best to try to adapt knifefish to pellet and other dry foods as soon as possible, but many will show a preference for frozen or even live foods despite the aquarist's best efforts. Avoid the use of feeder goldfish or livebearers as they may carry diseases and are not nutritionally suitable. Aqueon Tropical Granules Betta Treat Shrimp Pellets and Cichlid Pellets are good choices for small to medium-sized knifefish, while Monster Fish Medley can be fed to larger species like clown, African and featherfin knives. Small amounts of food can be fed after the aquarium light is turned off to accommodate their nocturnal feeding behavior. Remove any uneaten food in the morning to avoid water quality problems. For best results, rotate their diet daily and feed only what they can consume in 2 to 3 minutes, once or twice a day.
Knifefish Breeding - Intermediate
Knifefish breeding by private aquarists is rare, although several species are commercially bred.

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Ghost – White Leopard Dalmatian Ghost Knifefish 15cm
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White Ghost Knife Fish
The White Ghost Knifefish (Apteronotus albifrons) is found widely distributed throughout the streams and rivers of the northern portion of South America. They are most commonly found in fast flowing jungle rivers and streams, but also move out into the flooded forests during the rainy season.They use their thin elongated body to move in and out of tree roots and dense vegetation, where they look for insects, insect larvae and small worms on which to feed. Black Ghost Knifefish are considered somewhat shy compared to most Cichlid species that inhabit the same Amazonian water ways.
White Ghost Knifefish are best kept with tank mates that are not too boisterous or aggressive. Discus, Geophagus, Severum, Angelfish, peaceful Catfish, peaceful Cichlids and larger (6 inches or more) community species make good tank mates.
White Ghost Knifefish do well in fairly heavily planted aquariums and aquariums with tree root structures large enough for them to swim through. Ideally the aquarium should also have open swimming areas and areas of plants and root structure where the bright aquarium lighting is diffused. This will give the Knifefish a place to retreat to when it feels threatened or simply would like to escape the bright aquarium lighting.
Adult White Ghost Knifefish should have a larger aquarium (600 litres or more) in order to have enough territory for multiple specimens to coexist peacefully.
In a large aquarium, 4 or more specimens will be easier to keep than a pair as aggression will be spread out amongst the group instead of a single dominant specimen picking on a weaker one. As with other river fish species, clean water and low nutrient levels is critical to the long term health of this species. Due to the large size of this species, a quality canister filter or wet dry filter is recommended along with periodic partial water changes.
They are carnivores that prey mostly on insects and small worms in their native habitat. Aquarium specimens can be fed both live and frozen blood worms, tubifex worms or other similar meaty items. They can also be converted to eating other meaty foods like prawns, krill, earthworms, crickets etc. Most will also eat commercial dry foods like pellets and sticks. They should be fed daily an amount of food that they will consume with a few minutes. It is best to vary their diet so that they receive all the vitamins and minerals that they need in order to maintain a healthy immune system.
- Species – Apteronotus albifrons
- Common Name – White Ghost Knifefish
- Origin – Northern South America, Amazon
- Diet – carnivorous
- PH Range – 6.5 – 7.5
- Temperature – Tropical 26°c – 28°c
- Breed Type – Egg Layer
- Current Size – approximately 6cm (Grows to approximately 50cm)
- Sex – Un-sexed
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Black Ghost Knife: Care Guide (with Tank Mates & Diet Tips)
Not every freshwater aquarium needs a burst of vibrant color.
Sometimes you want something unusual as the centerpiece of your tank.
And if you want a genuine conversation piece? You couldn’t ask for better than the black ghost knife ( Apteronotus albifrons ).

Black ghost knifefish don’t attract a ton of attention with their monochromatic color scheme.
But when you start to dive into their biology, you find plenty of unique facts you can share with everyone that drops by for a visit.
Why not discuss the lack of a dorsal or caudal fin ? Black ghosts rely on their pectoral and anal fins to generate a fluid, wave-like motion – similar to that seen in a skate or ray.
It’s hypnotic to watch and allows them incredible maneuverability through the water.
Or you could touch on the electrogenesis . Similar to the electric eel , black ghost knifefish can generate and receive electric signals to help them navigate through the murky waters of their native regions.
And the same electric frequencies allow them to communicate with each other.
Of course, as unique as black ghost knifefish are, they’re also not for the faint of heart.
These fish present challenges beyond the scope of the beginner aquarist.
And if you’re not ready to handle such a fish? You may want to admire the species from afar.
At a Glance
In this article
In the Wild
Size: larger than advertised, black ghost knife lifespan, black ghost knifefish in communities, food and diet, breeding: exercise responsibility, black ghost knife health, black ghost knifefish: are they for you, the understated electric cousin.

You’ll find the black ghost knife in Argentina, Brazil, Paraguay, and Venezuela.
In particular, they frequent the river systems of the Paraguay and Paraná.
During the dry season, they stick to faster rivers and streams. But they head into the flooded forests during the rainy season.
Those waters come complete with heavy vegetation. That means plenty of obstacles – and not much in the way of light.
Of course, black ghosts are nocturnal. And they don’t rely on the moon or stars filtering down through the greenery, anyway. They have a better system.
Clustered along the skin of the tail, black ghost knifefish possess specialized cells capable of electric organ discharge (EOD) .
The electricity generated allows for electrolocation – navigation via an electric field.
It’s how the species “sees” in the murky, plant-filled waters.
But in the black ghost knife, the EOD plays another role. No, it can’t stun their prey (you’re thinking of the electric eel).
The fish control the frequency of the signal. And this allows them to recognize and communicate with each other.
Females produce a higher frequency than males. This allows potential mates to locate one another through the choked river systems.
And in confrontations, the EOD can settle a potential conflict. A submissive fish will increase their frequency, avoiding attack.
The black ghost knife name comes from the curved shape of their bodies.
You see a distinct taper at the tail, made more evident by the lack of the dorsal fin.
And with only a couple of white rings around the tail, you can pick out that slender, “blade” shape .
As to the “ghost” part ? That relates to local mythology. Tribes in the area believe that, when someone passes on, their spirit transfers into and inhabits the body of one of these unusual fish.
Add the two together, and you get a black ghost knife.

Like iridescent sharks , you often find juvenile black ghost knifefish for sale in the fish store.
The little “blades” look innocuous enough. And who doesn’t want an electric fish around? (Even if it doesn’t use the electricity to stun)
Unfortunately, many aquarists aren’t prepared for the adult size of a black ghost knife.
And a slow growth rate doesn’t help. Black ghosts only grow 4-5 inches (10-13 cm) a year – for the first five years.
Then they slow down. But the damage is usually done by that point.
At full adult length, black ghost knifefish reach up to 20 inches (51 cm) . And you CAN’T restrict them by housing them in a smaller tank (despite claims on certain sites).
Slow-growing or not, they’re going to surpass most aquariums eventually – and end up with aggression issues.
As you might guess, based on that SLOW growth rate, black ghost knifefish hang around.
With proper care (and suitable tank size), you can expect to see your electrogenic fish survive for anywhere from 10-15 years .
Despite that EOD ability, black ghost knifefish aren’t social . Oh, sure, they inhabit the same regions and often come in contact with each other.
But they can “jam” their signals when in proximity to one another to avoid sensory overload. (It’s a version of frequency adjustment)
As such, the species prefers to hang around on its own.

Once night falls (remember, they’re nocturnal), they venture out of hiding to search for food and swim around.
And as long as they aren’t feeling confined or squished into a space that’s too small, they’ll stay happy.
The aggressive reports come when someone attempts to keep a black ghost knife in a tank that’s too small.
Electroreception develops in species with poor eyesight.
And constantly bumping into everyone and everything because your tank’s itty-bitty? It’s going to cause a mean streak.
That said, it IS possible to house two black ghost knifefish together. You just need to make sure you provide enough room.
Space will prevent unwanted aggression from breaking out. Don’t go above two, though.
While you can conceivably provide a tank large enough (assuming you have the room in your house), you’re going to end up with an overlap between the electric fields.
And that’s going to stress the relationship between the fish. Black ghost knifefish and stress DON’T mix.
So how much space does one of these slow-growing, larger-than-expected fish need?
To accommodate the electric field generated, enclose the swimming room, and provide the necessary hiding spaces for ONE black ghost knife, don’t go smaller than 100 gallons (379 l) .
If you plan to bring a second black ghost into the mix, you need to add a full 100 gallons (379 l) MORE.
This is the only way to prevent aggression from cropping up as they swim and hunt for food around the tank. (See why you should set two as the upper limit?)
You also need to take care with all of your filters.
Some black ghosts have ended up in canister filters or the attached tubes in their need to escape light (those eyes are tiny but sensitive). A cover should prevent any accidental “escapes.”
Water Conditions
Black ghost knifefish come from tropical regions of South America. As such, you want to keep the water temperature suitably warm.
This means sticking as close to the 73-80 ° F (23-26 ° C) range as possible.
In the wild, black ghosts swim in neutral, soft waters. So you want to keep your pH range between 6.5-8.0 and your hardness level down around 0-10dH.
You DO have flexibility, though. After all, it’s not like they’re swimming in pristine river systems.
Of course, when it comes to water quality, you need to up your game.
Black ghosts don’t possess scales. That makes it MUCH easier for them to contract an illness. And unhealthy water conditions (or stress) will often lead to disease.
If you can spring for it, you may want to add a UV sterilizer .
It’s an investment, but it’ll help prevent different pathogens from invading your aquarium. (And it won’t stress out your black ghost knife to have the sterilizer around)
Decorating the Black Ghost Tank

You have an impressive aquarium to fill. And black ghost knifefish come from river basins FULL of logs, rocks , and plants.
That means you have plenty of opportunities to decorate a stunning tank.
Starting from the bottom, you want to choose a soft substrate.
Black ghosts feed along the bottom. And without scales to protect them, they can end up with scratches and cuts if you use larger gravels rather than sand .
As to the remainder? These fish aren’t particular about their décor.
You’ll want hiding places, but you can use anything from driftwood to rock structures to artificial caves.
As long as you provide space large enough, your black ghost will stay happy.
The same with plants. Black ghost knifefish are carnivores. So they won’t sample the foliage.
And floating plants will help cut down on the glare from any lights. Feel free to choose any of your green favorites:
- Amazon sword
- Dwarf water lettuce
- Ludwigia repens
- Red root floater
- Water wisteria .
You may also want to invest in a “ghost tube.” Black ghost knifefish are nocturnal. But most aquarists? They aren’t.
If you’d like to see your sleek fish now and then (or show it off), a ghost tube can help you do so – without causing stress.
A ghost tube is nothing more than a clear plastic tube set into the tank.
The EOD assures the black ghost knife it’s surrounded by a solid structure and, thus, safe.
Meanwhile, you can see the fish the entire time. It’s a win-win situation for everyone.
As long as you’ve done due diligence in providing enough room for your black ghost knife to navigate and explore in the first place, there’s no reason you to omit them from a community tank.
Space is the biggest predictor of their aggression. And once that’s sorted? They’re fine.
Of course, black ghost knifefish ARE predators. So when you start to plan your community, you want to look for fish of comparable size.
And you should consider species with peaceful temperaments. Those electric cells CAN’T function for defense, after all.
Ensure that everyone keeps the space they need. This goes double if you have a pair of black ghosts in residence.
But as long as no one’s getting their fins stepped on, you can pair up any of these tank mates:
- Electric blue acara
- Silver dollar .
Incompatible Species
Obviously, that leaves out smaller fish. Not because black ghost knifefish will turn into bullies (that isn’t in their temperament).
But they WILL decide those little fish are snacks. For instance, guppies make lovely midnight snacks (literally).
A few aquarists HAVE managed to keep some community species – such as celestial pearl danios or neon tetras – with their black ghost knifefish.
But only while their predator was a juvenile . Once it outgrew the tank mates, they became its food.
Along the same lines, you don’t want to set up a mixed aquarium. Shrimp and snails are part of a black ghost’s natural diet.
And those invertebrates are easy to find with electroreception. In no time at all, you’ll find yourself with a fish-only tank.
Black ghost knifefish are strict carnivores . They developed electrolocation to hunt in the dismal waters of their river systems, zeroing in on the signals sent out by their prey.
And you’re not going to convince them to make a change to commercial fish food.
This means keeping a healthy stock of frozen or live protein sources. And even though they’re not colorful, you should still keep a variety on hand.
Luckily, black ghosts aren’t picky. You can choose from any of their favorites:
- Brine shrimp
- Tubifex worms.
As nocturnal fish, you WILL need to think about when you feed your black ghost knifefish.
Tossing food in while they’re sleeping won’t work. A once-daily feeding in the evening (or even before you head to bed) works best.
Watch the amount of food your black ghost eats carefully. Overeating’s a common problem.
You don’t want a fat fish (that isn’t healthy). And you don’t want to struggle with the extra waste that will result.
If they can’t finish what you offer in a few minutes, cut back.
You’ll find plenty of theories for breeding black ghost knifefish. However, it isn’t a process with guaranteed results.
Commercial fisheries in Indonesia have mastered the technique, but they’re holding the secrets close to the vest.
Due to the uncertainty over the process, you may want to avoid attempting to breed this species.
It’s the most responsible route, particularly for a unique species that already struggles with proper management.
If you do choose to proceed? Ensure you follow strict guidelines for care.
Male or Female?
You won’t find external differences between male and female black ghost knifefish.
And the average equipment available to an aquarist won’t allow you to detect the electric frequencies discharged by the two.
It’s the first hurdle in attempting to breed this fish successfully.
Rolling the Dice
Assuming you DO have a pair of black ghosts, you next need to set up your tank for success.
And that starts with keeping everything as dark and quiet as possible. Black ghost knifefish can’t see well. And any little thing holds the potential to cause stress.
The assumed optimal breeding temperature for the water is around 80 ° F (26.6 ° C). Stability is key.
You also want to perform 50% water changes every few days to simulate the beginning of the rainy season (when black ghosts move into the flooded forests and begin spawning in the wild).
Beyond that? We don’t know much. The pair will lay and fertilize their eggs in a cave, log, or another sheltered spot within the tank.
The eggs are yellow, and they take around three days to hatch . The fry can eat infusoria, brine shrimp nauplii, and powdered fry foods.
Without scales to protect them, black ghost knifefish often end up with skin diseases.
This means anything from ich to bacterial infections from scratches. And since their nocturnal behavior keeps them active while you sleep, many aquarists miss crucial signs.
At the first sign of a scrape or wound, you need to monitor your black ghost. Even if that means staying up a little longer every night.
Is it healing? If you don’t see healthy progress, you need to start seeking treatment.
The same goes for when those white ich spots appear. Luckily, they’re easy to pick out against the black skin.
And you’ll notice a behavioral change as your black ghost starts itching itself against anything and everything.
Stress is another major health concern among black ghost knifefish.
The fish grow stressed as water conditions fluctuate, diet shifts or noise or light go up.
And the more uncomfortable they feel, the greater the risk of illness or even death. A stable environment works best.
You can find juvenile black ghost knifefish in stores or online for around $7.
They’ve grown in popularity, and you shouldn’t have trouble finding one if you have your heart set on bringing an “electric” fish into your tank.
However, take a look at the size of the fish on offer. If the fish is over 5 inches (13 cm), it’s probably wild-caught.
This means you need to extend your quarantine period . Wild individuals often have protozoa, worms, flukes, and bacterial infections.
Smaller black ghosts may cost more, but they’re likely captive-bred.
This alleviates pressure on the wild populations, and it means you won’t have to worry about all of those potential pathogens.
Not to mention they’re usually hardier. It’s worth the added expense.
Black ghost knifefish aren’t dazzling – in their colors or with their electroreception.
However, how many people can say they have an electric fish in their tank?
If you’re willing to set aside the space necessary – and meet their water quality needs – you couldn’t ask for a better fish.
Do you have black ghosts? What’s the largest size you’ve seen your black ghost knife grow?
Have you set up a ghost tube?
Let us know your questions and stories here!
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Resources » Freshwater Fish » Black Ghost Knifefish
Black Ghost Knifefish Care Guide: All You Need To Know

Black Ghost Knifefish are very popular – they are a mesmerizing and elegant fish that will steal your heart in no time.
From ghost stories of tribes in South America to electrogenesis, this fish will be an entertaining conversation starter in your home.
This fish is almost an exception to the rules of nature.
It does not have any scales or fins and its tail looks like a rod.
Read on to find out more about keeping Black Ghost Knifefish in your aquarium, from their ideal tank conditions to feeding and the best tank companions.
TABLE OF CONTENTS
Black ghost knifefish facts & overview, habitat and tank conditions.

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The Black Ghost Knifefish is one of the most popular Knifefish. It was originally known as Gymnotus albifrons and Apteronotus passan . But today this fish is known as Apteronotus albifrons .
Other common names which it is known by include the Apteronotid eel and the Black Knife.
An interesting story about this fish is one which is told by South American tribes. It is believed among the tribes that live in the Amazonian jungle, that the souls of the dead inhabit these fish.
The common name of this fish, the Ghost Knifefish comes from these stories.
These fish are mainly nocturnal animals and they use electrolocation to navigate dark waters.
This fish has quite a long lifespan and if cared for properly they will be your companion for 15 years.
It is readily available online or in pet shops for around $7.
Black Ghost Knifefish are tropical freshwater fish from South America. These are nocturnal fish that are most active at night and rest during the day.
As they are most active at night, their eyesight is not well developed, so they hunt and communicate through an electric field.
They are quite shy and not very social preferring their own company – they can become quite aggressive if kept with other Knifefish. After they settle down in the new environment, they will come out from their hiding place during the night and swim mostly near the substrate or foliage and plants.

The Black Ghost Knifefish, as their name suggests, is entirely black except for two white rings on its tail and a white stripe on its nose that often extends along its back.
Unsurprisingly, it is also the shape of a knife – it has no caudal or dorsal fin.
Their body is flat and elongated, reaching up to 20 inches long when fully grown. The anal fin stretches along the body from the belly to the tail. This gives it an elegant swimming style.
This species of Knifefish does not have any scales. For this reason, this fish is very sensitive to water conditions and infections as it lacks the extra protection given by the scales.
Black Ghost Knifefish can both emit and receive electric signals . The electricity is produced by an organ found in the tail. These cells sit on the skin of the fish and are used for both communication and electrolocation.
This electrogenesis is interesting when looking at the differences between sexes. While there is no apparent dimorphism between the two sexes, it has been found that females emit higher frequencies than males .

The Black Ghost Knifefish is found throughout the Amazon River and its tributaries , from Venezuela and Paraguay all the way down to the freshwater basins in Peru.
These waters are full of vegetation with plenty of nooks and crannies to hide. The waters are usually quite murky with low lighting and moderate water currents.
The water would also be warm with a fairly neutral pH.
The substrate beneath them would be soft sand that would not scratch, which is important since they are scaleless.
These tropical freshwater habitats are home to a wide variety of insects, which provide plenty of insect larvae for Black Ghost Knifefish to eat.
A captive Black Ghost Knifefish needs an environment that resembles their natural environment as closely as possible. This is simple to do, we outline how to below.
As they are quite shy fish, they appreciate a tank with many hiding places. Smooth rocks and plants are must-have features for them in your aquarium.
Remember, this is a scaleless fish so you should provide a fine substrate to avoid injuries – use sand or a very fine gravel mix. The tank should have low lighting with a strong to moderate water current.
As the water in their natural environment is quite murky, they are tolerant to a range of water conditions. However, the best water parameters to allow your fish to easily settle are a temperature of 73.0-82.0°F, a pH range of 6.0-8.0, and a hardness of 5-19 dGH.
Black Ghost Knifefish are freshwater species and can not tolerate any brackish conditions.
Some hobbyists find their fish hiding in the canister filter or tubing. Make sure that when you are setting up the tank, use pre-filters or cover any open inlet tubes to avoid surprises.
Since they are scaleless fish and are prone to infections, a UV sterilizer is a good purchase to avoid complications as it helps to keep the water free of diseases.
What Size Aquarium Do They Need?
Black Ghost Knifefish are large fish and need a large aquarium of at least 100 gallons.
How Many Can Be Kept Per Gallon?
These are not an aggressive species toward other tank mates such as peaceful Cichlids, however, it becomes very aggressive when sharing small spaces with the same or similar species.
If you choose to keep these fish together, you will need to allow a minimum of 80 gallons per fish.

Even though they are considered semi-aggressive fish, they are perfect for a community aquarium.
The ideal community for this fish is other peaceful similar size fish such as peaceful Cichlids or Catfish .
Black Ghost Knifefish will start to become aggressive if they are limited to small spaces and if they don’t have enough hiding spots.
They also become quite boisterous if kept with members of the same species or similar species.
Make sure any tank mates that you add are at least 6 inches in size and are quite peaceful. The perfect community can be created using peaceful Catfish, Angelfish , large peaceful Cichlids, Discus and Corydoras .
Corydoras are great companions because they will also help keep the aquarium clean.
Tankmates will of course have to have similar preferences regarding the water conditions too. This rules out species like Goldfish which prefer cooler waters.
While your Black Ghost Knifefish is growing, you might be able to keep it with smaller size fish such as Tetras , Guppies , Barbs , and Rasboras .
Small crustaceans and gastropods (such as shrimps and snails) are not a good match as they are the perfect food for your Black Ghost. They will likely be eaten during night hours.
Don’t keep these fish with other aggressive fish, or fish that are small enough to be considered food.
Keeping Black Ghost Knifefish Together
Keeping Black Ghost Knifefish together is not the best idea unless you can provide a tank large enough to let them establish and develop their own territory.
Black Ghost Knifefish are recommended to more experienced aquarists as they can be challenging to keep.
This fish has no scales and is quite sensitive to diseases and chemicals in the water. This is why you might want to consider investing in a UV sterilizer.
One thing to keep in mind for this fish is to never use copper-based medicines as it is very toxic to them.
Knifefish are prone to skin flukes such as the ich disease . Your fish will start to itch and rub themselves around the tank, however with the right treatment they should heal quickly. Raise the temperature up to 86°F if you spot any infection. Higher temperatures interrupt the parasite life cycle preventing reproduction and growth.
They are commercially bred in Indonesia which is great for the wild populations of South America.
When you are buying one, look at the size of it. If you get offered an individual bigger than 5 inches, it’s likely to have come from the wild.
If an individual has come from the wild, it might carry parasites and diseases. Make sure you place them in quarantine to ensure no unwanted organisms enter your pristine aquarium.

Black Ghost Knifefish are a carnivorous species . In the wild, they feed on insect larvae, juveniles, and small fish, and worms.
In your tank, this won’t change much and they should be fed with fresh or frozen food such as bloodworms , brine shrimps, or blackworms.
Other alternatives are tubifex worms, krill, prawns, or crickets. You can also try to feed them pellets or flakes, however, it might take a while for them to get used to these.
They tend to avoid dry food.
It is important to keep a varied and balanced diet to ensure that your fish will receive the right vitamins and minerals for a healthy immune system.
They should be fed daily with an amount of food that they can eat in a few minutes. They are nocturnal animals and should be fed in the evening or at night.
Initially, they might struggle to feed. Black Ghosts are quite shy and will take a while to come out from hiding.
Some hobbyists have also been successful to feed their pets with their own hands. This might be something that you want to try, but you will have to be patient. It can take a while to train your fish, but it will be very rewarding.
Black Ghost Knifefish are not commonly bred in tanks. Whilst there are claims from some hobbyists that they have managed to breed them, the methods are sometimes disputed.
Some specialized commercial fisheries in Indonesia have managed to breed them. However they are quite secretive about their success, so this still remains a mystery.
The most common factors to encourage breeding are:
- Large tanks (at least 100 gallons)
- Densely planted aquarium
- Lots of hiding places
- Flooding and draining the tank
Eggs are laid in a cave or a similar sheltered area. The eggs are yellow and about 0.08 inches in diameter; they usually take 3 days to hatch.
The parents should be separated from the eggs once they are laid. In the wild, it is common for the parent to eat the eggs; they do not appear to have any strong parental instincts.
Once the fry are released they will need to be fed a selection of small foods. These could be infusoria, baby brine shrimp, and/or broken-up flake foods.
Most aquarists do not reach the stage of raising Black Ghost Knifefish fry. If you manage it, may sure you share your story to help others and shed light on the mystery.
Black Ghost Knifefish are very popular, they have a mesmerizing swimming style and can be very friendly once settled in the tank.
Similar to most eels , Knifefish has an electro-sensory system used for location detection and communication.
As they are quite sensitive to diseases and can be a bit picky with food it is recommended that you gain some experience before keeping these fish.
This is a nocturnal fish and will be most active at night. They are carnivores and will mainly feed on worms, brine shrimps, and insects.
Over the years, aquarists have successfully trained their Knifefish to eat from their own hands – if you want to dedicate some time to this adventure, maybe you can get them eating from your hands too!
Have you already kept a Black Ghost Knifefish? Tell us about your experience in the comments section below…
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25 comments.
A peaceful and shy fish. I am keeping it with some jewel cichlids, angelfish, bala shark and a silver arowana.
I keep a Ghost knife in a tank close to the sofa. It Hid all day until I turned on a blue tooth speaker close to the tank and played music through it . I looked round to see it swaying about on its tail next to the glass in the middle of day. It started moving about the way they do mimicking an underwater ballet in reverse. It’s picking up the Bluetooth signal from the phone . This excited it and makes it feel it more at ease when it senses it . I turn off the blue tooth and it’s back into the log . I keep the phone and speaker on all day now so it can groove to the sounds. Could these Bluetooth signals mimick other fish in it natural habitat ?
Hi Gary, thanks for sharing this, this is fascinating! I have no experience of this happening before. Many thanks, Robert
This is absolutely fascinating! I just got my first black ghost knife fish. I’m going to try this to see if I get similar results!
My knife fish has a bulge under its chin? It has been growing slowly over the last 6 weeks. Would you have any idea what this could be?
Thanks Stuart
Hi Stuart, it’s difficult to tell without being able to see it, but a single lump is most likely a cyst. Probably lymphocystis which is viral. To treat this you will need to do all you can to reduce stress, make sure water parameters are perfect, feed regularly, remove any fish which are causing stress etc. Thanks, Robert
Ive been keeping a BGK since 14th March, 2020 now. We still havent named her yet. She is my elder brother’s favourite fish along with a Koi we keep in our pond. My bro has a special affinity for her out of the entire tropical lot.
Ill share some of my observations here.
The only fish my BGK is aggressive or defensive against is my Common Pleco. Idk why but the pleco is the only fish the BGK attacks whenever the pleco gets too close. Since the pleco is a pretty tanked up fish, I dont worry about it. The pleco has learned to stay away from the BGK’s territory now.
African Cichlids try to nip at the underbelly and fins of my BGK. She had been shredded like a paper by the cichlids so I gave the stupid cichlids away. She recovered in no time.
She likes to eat crustaceans. I had an Electric Blue Crayfish in the tank with her. After a molt, the BGK devoured the cray before he had a chance to harden up his shell. Ever since that, The BGK has had quite a growth spurt as she grew 1.5 inches in length in less then a week! I still get amazed by just remembering it
The only tankmate my BGK is afraid of is my turtle. I have a Brown Roofed Turtle in there with her. The turtle has claimed no lives ever since the day I got him (19th March, 2020). He gives free rides to the shrimp I feed my BGK on the back of his shell.
In the beginning, the BGK would come to the surface to eat pellets and freeze-dried worms. She did so for quite a few months but then she quit coming to the surface. Now she accepts anything that sinks to the bottom. Every once in a while, I do witness her going to the surface but its a rare event now.
In a 150 gallons, I keep my BGK with four Tiger Barbs, six Silver Kuhli Loaches, a Common Pleco, a Dwarf Gourami, an Indian Barred Spiny Eel, and a Brown Roofed Turtle (and countless Malaysian Trumpet Snails because of the sandy substrate). Everyone gets along fine with the exception of a few baby snails getting eaten here and there by the fish.
I hope some of these accounts fascinated you because they def fascinated me!
Have had my ghost thats his name for 2 months sleeps in the canopy of the plants i stroke him to wake him up and feed him by hand love this fish
So kinda new to this, but I got a ghost and I am having problems feeding him. it seems like the other fish eat the food before he comes out and gets it. I have 150 gal tank. could use some ideas please. thank you.
When i was a kid, I had one I my 10gal tank. It grew to about 9-10 inches. But it lived successfully for 10 years. It did die from ick when I introduced a new cave for it though. It had an angel fish and pleco living with it.
Bought 3 ghost fish about 3 years ago. A week ago I notice I have a baby about 1-1/2″ long. I’m in shock. Never saw any eggs. I’m very surprised I didn’t suck them up while cleaning the tank. Baby stays near the top on the leafy plants. Eats the tiny pellets and gets very active at feeding. Now what? Anybody got any advice?
Hi Robert, I’ve had Hoover for 3 years now in a 20 gal tank. She’s a stunner and super responsive. Eats during the day with the other fish but I notice lately she eats at night as well as the population in the tank has dwindled to only 4 quests left. I have been planning to get a larger tank but was waiting to finish a remodel. Moving a 20 gal tank as opposed to a 75 gal tank is easier. Just in the last few weeks I noticed Hoover had a whitish film on her and wanted to deal with this organically. After some research I choose to go with a salt treatment as the article said this is like electrolyts and would help the tank. As soon as I started the treatment I noticed Hoover in a panic. Back to more research, I found your page and read that Ghost Knives are intolerant to brackish water. I have flushed the tank twice so far taking out 75% of the water and replacing with fresh. Hoover has settled down with a more regular breathing pattern but is still in shock and not swimming. I am watching closely and am debating whether to do another flush….what would you suggest and hope you get back to me soon.
UPDATE…. Hoover is alive and swimming today! I am so delighted! I only did two flushes on the tank figuring that would be enough disruption for her. So lucky to still have her. They are a special fish! Thank you for all the info concerning ghost knives! What would you suggest to use to rid the tank of the white fungus on her body?
I had two black ghost knifes. The first one, which I think was a male, became very friendly. I could pet him and he began to rest inside my hand. I got a second one, which I suspected to be a female. I noticed what I suspected was mating behavior consisting of swimming around “dancing” with their bodies. Low and behold, one day when I was cleaning the tank, I picked up a rock and a baby knife swam out. I moved some sub strata and saw another one, that was much younger. The female had been guarding the first baby. Sadly, I think one of the adults ate the babies. These fish are amazing! Their undulating swimming motion is beautiful to watch as is their ability to swim both forward and backward.
Hi, I have a pair of clown knife fish measuring approx 20cm long. I have had them for over 2 years now. The power was out at home and being winter in Cape Town the temperature of the water dropped. The fish were acting very strangely before I realized what the problem was. They were vertical (nose down)and not moving at all, like really dead still. I thought they had died. I added some warm water and they recovered in about an hour or so. They, however developed a slimy coating much like a mucous all over their bodies. The mucous was clear but visible and slowly came off their bodies as the temperature increased. I scooped off the mucous that was now floating on the surface. I am guessing that this mucous protected the fish while the temperature was too low and the fact that it was in a stasis form was its way of protecting itself. I just need some clarification.
How black ghost knifefish swimming method improved their function in the environment and survival?
They sleep alot i agree and allways hide i got 3 on one 110 gallon
My ghost fish started hiding by the filter nut as it likes to sleep I didn’t think it was a problem. Today I cleaned the tank but after some minutes I saw that it wasn’t moving. I tried moving it with my fingers but it won’t move. It is dead?
I had my ghost knife for about 10 years, he was already around 25 cm when he was given to me. He was a part of the family loved by everyone but unfortunately we lost him about a month ago. John was his name and he was very friendly eating out of our hands and always rubbing his cheek against our fingers for a pat before taking his bloodworm. He was amazing to watch and would always make our day by putting on little performances for us whenever he knew we were watching. I highly recommend a ghost knife to anyone with a love of unique fish. I will be purchasing a new one eventually when i am ready.
I have 8 Ghost knife fish in a 4ft tank. The largest fish is around 12 inches long. They don’t have any special care and the other month I noticed a smaller fish around 2 inches long…. upon further investigation I have seen a few other baby fish about 1 inch long, so I assume they are breeding. Reading ghost fish articles I am led to believe that these fish are difficult to breed. I dispute all the claims that tank breeding is almost impossible.
Hi. I’ve had a black ghostknife fish for about 11+ years which is why I just checked their lifespan. His name is Avraham but not sure if he’s a male. He’s beautiful to watch and I have a couple catfish in with him plus a couple goldfish. They all get along really well but it is a large tank. Black Ghostknife are my favourite fish…
I took agree I love my B.G.K.I AM PICKING UP 2 TODAY .I LOVE READING ON THEM WHEN I GET THEM I WILL SHARE PIC.
Hi I’ve had my knife fish for about 2 1/2 years it was about 3 inches long now he’s just under 13 inches he’s very tame takes meal worms from our fingers and is so beautiful and very loved its shame I can’t leave a video of him how big he is
I have been keeping Ghost Knifefish for aeound 6 years and they breed quite happiy. I get 2 or 3 new fish every year. There are no special conditions as you say in your article, they just get on with doing what they do
Funny you mention we Indonesian keep secrecy about breeding which in reality we don’t, most hobbyists probably can’t breeding is due wrong setup or let parents on the tank after they lay eggs which not good idea since they will love eating them. Keep look at hard leaves plant because ussually they put their egg on that and makes sure the fry get good amount of oxygen
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White Ghost Knife Fish 6cm
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Care Guide for Black Ghost Knifefish — 18-Inch Electrical Oddball Fish
We get a lot of requests for this care guide because knifefish are such unusual-looking curiosities with an undulating fin that allows them to swim both forward and backward. While there are many kinds of knifefish, the black ghost knife (BGK) is the most readily available in the pet trade and often attracts the attention of beginners. Unlike your average betta fish though, it is a considerably larger pet that requires a ton of room and may live for over a decade. Before you make the commitment, let’s talk about what it takes to keep this intermediate-level oddball fish happy and healthy in the long term.
What are Black Ghost Knifefish?
Apteronotus albifrons is a South American nocturnal fish that has weak eyesight and instead uses electrical signals to navigate its surroundings. The common name “knifefish” comes from the fact that it has no dorsal or caudal fin, giving it a blade-like appearance. Instead, an extended anal fin runs along the bottom edge of its body and ripples back and forth like a wave, allowing the knifefish to maneuver bidirectionally between tight spaces.
Most black ghost knifefish are captive-bred nowadays and may cost $15-20 or more, depending on the size of the individual. Many times, juveniles are sold in crowded tanks and may get into scrapes with other fish, so make sure to get a healthy one that has both of the white spots on its tail. Given that this fish can live as long as a pet dog, consider asking the store employee to feed them first so you can confirm your new knifefish is eating well before taking it home.

Find a healthy knifefish that has a good weight, active behavior, and its entire tail.
How big does a black ghost knife get? They can get pretty large if you are feeding them enough, so don’t be surprised if your baby knifefish matures into a 14- to 18-inch (35-45 cm) beast.
How fast do black ghost knife fish grow? In our care, we have seen them shoot up to 8 inches (20 cm) in the first year, and then the growth rate slows down to about 2 inches (5 cm) a year.
Is the black ghost knifefish hardy? Many people call them “sensitive” fish that don’t live very long, but that hasn’t been our experience. The keys to our success include feeding them really well, making sure they don’t get picked on, and maintaining good water quality, as you would with any other fish. Usually, fish can handle one stress factor, but multiple stress factors will increase the likelihood of health issues.
Can a ghost knife fish shock you? No, it is considered to be a weakly electric fish, in contrast to a strongly electric fish like the famous electric eel that can stun its prey. The electric organ of a knifefish generates a very weak electrical field, and then it has different sensing organs that can pick up the slightest distortions to this field, similar to a radar system. This detection system helps the knifefish to navigate its surroundings, locate prey, and communicate with potential mates or intruders.
How to Set Up an Aquarium for a Black Ghost Knife
Let’s talk about tank size. A 55-gallon aquarium might be okay for the first year, but it is too small for the long term. A 75-gallon fish tank is the next upgrade that may last for a few more years. Ultimately, we recommend getting a 120- or 180-gallon aquarium for an adult black knife fish. They generally do fine with pH of 6.8–7.8, temperature between 75–82°F (24–28°C), and at least 5° (90 ppm) GH. Create a heavily decorated setup with low lighting and lots of nooks and crannies — such as clear PVC pipes, rock caves, pleco caves , large driftwood, and aquarium plants . As they grow bigger, upgrade the size of their caves and tunnels so they can feel completely safe and surrounded in their shelters.

Plecos may quarrel with your knife fish over the best hides, so provide more caves if needed.
Is the black ghost knifefish aggressive? In the right conditions, they can live in a community aquarium with other similar-sized, peaceful fish. You don’t want any tank mates bullying or outcompeting them for food, such as aggressive cichlids or fast rainbowfish. Also, your adult knifefish will happily eat neon tetras and any other small fish that can fit in its mouth, so avoid any nano fish when it gets bigger.
What fish can live with a black ghost knife? Hobbyists have kept adult BGKs with Geophagus “eartheater” cichlids, peaceful catfish, angelfish, and other friendly tank mates larger than 6 inches (15 cm).
Can 2 black ghost knifefish live together? We don’t recommend it since problems tend to arise. Knifefish are territorial and don’t like sharing their space with other electric fish, such as baby whale fish, elephant nose fish, and other knifefish. Obviously, anything is doable if you have a large enough aquarium, but most people tend to keep ghost knifefish in undersized tanks.
What do Black Ghost Knife Fish Eat?
Thankfully, they are not too difficult to feed and eat a primarily carnivorous diet. Despite being a bottom dweller, they willingly go after both floating and sinking fish foods. Ours enjoy a variety of worms, bloodworms, brine shrimp, pellets that fit in their mouths , and freeze-dried foods . As mentioned before, they will predate on small fish and invertebrates once they’re old enough.
Black ghost knives can be a bit shy at first and want to spend all day in their favorite hiding spot until it’s time to eat. Therefore, many people have trained theirs to eat out of their hands or from the water surface by using floating foods.

Black ghost knives can be trained to swim up to the surface and eat from your hand.
Do black ghost knife fish eat flakes? Flake food may not be nutritionally dense enough for knifefish in the long run, especially since it is easy for them to get outcompeted for food by other fish. That is why we tend to prefer frozen, freeze-dried, and pellet foods to help them maintain a healthy weight.
This showpiece fish is such a fun and cool-looking species to own. If you have done a lot of research and are willing to get a monster tank for its home, the black ghost knifefish may be the right pet for you. While we do not ship fish, check our preferred online retailers to see what they have in stock.
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Caring for Black Ghost Knife Fish (Tank Setup, Food, Tank Mates, & and More)

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Are you ready for a thrilling journey to learn about the remarkable Black Ghost Knife fish? This species can generate and receive electric signals, navigate through murky waters as well as survive in their natural habitat. We’ll cover all aspects of this fantastic creature – from its distinctive attributes, tank setup, feeding habits to potential companions within an aquarium setting. As if that were not enough.
We shall also explore how challenging it is to breed these ghost knife fish plus steps needed for providing them with optimum care. Are you game? Let’s jump right in!
Key Takeaways
- Black Ghost Knife Fish require a specific environment and diet to thrive.
- They are a peaceful fish that is bullied easy, but also gets very large
- Choose your tankmates carefully, making sure they are peaceful and of similar size & temperament
- Meaty foods are best for them. Flake foods are not enough
- Practice responsible breeding by providing the correct conditions for fry growth & nutrition
Species Overview
Introduction.
The Black Ghost Knifefish is a fascinating freshwater species from South American rivers with abundant vegetation. It utilizes its electric organ discharge (EOD) for communication and orientation in the dark, making it one of the most remarkable electric fish on earth. Successfully keeping this unique creature requires knowing what habitat, tank setup and diet to provide – understanding these areas is key when considering adding a Black Ghost to your aquarium environment.
Origins And Habitat
The Black Ghost Knifefish is found across the Amazon River drainage area. This includes parts of Venezuela, Paraguay and Peru where tropical freshwater habitats are present. These environments feature dense vegetation, soft sand substrate and low lighting, an ideal habitat for a black ghost knifefish to reside in naturally.
In terms of dietary habits, these carnivorous freshwater fish feed on different insect larvae and adult species as well as their larvae so it’s essential that aquariums which house feed them lots of meaty foods in order for them to continue growing and to stay strong.
Electric Abilities
The Black Ghost Knifefish has an extraordinary electro-sensory capability that makes it stand out from other species of fish – its electric organ discharge (EOD) 1 . By deploying this EOD, the ghost knifefish can navigate murky water using electrolocation. Essentially utilizing a surrounding electrical field as though they all ‘seeing’.
This is especially handy in their natural habitat, where light conditions are usually poor. They have poor eyesight, so this feature allows them to navigate around.
When paired with others of the same kind and through use of its EOD emission capacity, these weakly electric fish communicate among themselves. Even though you don’t need to worry about any shocks coming your way when encountering them directly – the electricity aspect plays a major role in their day-to-day existence which ultimately serves to make them distinct amongst all other kinds of aquatic life!
The Black Ghost Knifefish is an eye-catching species with its distinctive traits and electric abilities. Its body is thin, long, curved without a dorsal or caudal fin whereas the pectoral and anal fins provide locomotion instead of usual fins. The coloration consists of black primary shade complemented by two white rings on tail as well as a stripe usually extending from nose to backside that adds up more complexity in appearance.

It has no scales, which increases sensitivity to changes in water conditions and increases vulnerability against diseases – making it even more important for proper care through suitable environment understanding, especially regarding this fish’s unique features.
When selecting these fish from a fish store, look for the white markings on the tail. They should have double white marks. If they are missing this, it is likely that the fish has been nipped or bullied. You will want to avoid fish that have been harassed as they are under too much stress to be transferred successfully. Bullying is common in crowded tanks – and local fish stores are known for purposely overcrowding their tanks.
Size And Growth
When you want to get a Black Ghost Knifefish, it’s important that you take into account their size. These fish can reach up to 20 inches (51 cm) in length and are capable of growing as much as 8 inches (20 cm) during the initial year. The growth rate slows down to about 2 inches per annum after the first year, faster in larger tanks. This has an effect on tank requirements along with what other species of fish could be housed together.
Tank Size And Requirements (Black Ghost Knife Fish Care)
When setting up a habitat for the Black Ghost Knifefish, it is important to take into account their size and unique traits. An aquarium of at least 100 gallons (125 galloons is recommended) should be provided per individual. Adding an extra hundred if there are two or more fish as they may act aggressive with one another.
Replicating natural environment by decorating with soft substrate along with providing places where your Black Ghosts can hide will certainly improve its well being, enhancing its life span significantly.
Water Parameters And Conditions
To ensure a safe environment for the Black Ghost Knifefish, it is essential to maintain certain water parameters and conditions. The fish thrives in an aquarium with 6.0-8.0 pH level, 5-19 dGH hardness and water temperature between 73°F – 82°F.
Stability of these values should be a priority at all times since sudden changes can cause great stress or even illnesses to this species called the ghost knifefish (Black Ghost). To guarantee that tank water stays clean & free from any pollutants, frequent testing as well as regular partial water changes are extremely important in order to keep them healthy!
Tank Decorations And Hiding Places
Providing a range of hiding spots such as clear PVC pipes, rock caves, pleco caves and driftwood alongside aquarium plants is very important for the health of Black Ghost Knifefish. Keeping low levels of lighting in their tank will allow them to feel most at home due to their nocturnal nature.

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In order not to hurt its delicate skin, it’s also crucial that you use soft substrate like sand on your bottom bedding rather than gravel or stones which are found more commonly with other fish species habitat-wise. By replicating what they would find in their natural surroundings, the Black Ghost Knifefish should thrive happily when living within an aquarium environment!

Natural sand is excellent for bottom feeder fish to forage around in.
Looking after your Black Ghost or Knifefish involves giving them a balanced diet to meet their needs. As carnivores, they require an adequate supply of live or frozen protein sources for nourishment and strength in immunity. For best results, feed the fish just once every day during twilight hours as this is when it tends to be most active being nocturnal fish. Keeping up with such regular dietary intakes will allow you to ensure that your fish stays healthy while properly fed.
Preferred Foods
Black Ghost Knifefish should be provided with a variety of meals that are similar to what they would find in their natural environment. These may include things like live or frozen items such as bloodworms , brine shrimps, black worms, tubifex worms and other sources of protein like krill and prawns.

Frozen bloods are a great source of protein and a fish source fish naturally respond to. Very filling and works for just about any fish
Although they can also consume pellets or flakes , it might take some time for them to get accustomed to these food forms too. Flake food is also not going to be enough substance for these fish. Thus providing the right diet is important if you wish your Black Ghost Knifefish stay healthy and strong over time!
Feeding Schedule
Black Ghost Knifefish, which are nocturnal creatures, should be given their meals once a day in the evening as this is when they are most active. It’s essential to note how much your fish eats and not let it overeat because it can lead to declining water quality – if there isn’t any noticeable decrease after only a few minutes then reduce portion size accordingly. When introducing them into an unfamiliar environment try mimicking its natural habitat so that it will feel comfortable enough to start eating regularly again.
Social Behavior And Compatibility
The Black Ghost Knifefish is a solitary creature that emerges in the evening to hunt for food and likes to be on its own. If given enough space, they can exist amicably with other fish. Though if kept in too small enclosures, aggression may ensue. When selecting tank mates it’s vital to take into account their size and nature so to guarantee peaceful coexistence within a community aquarium.
Black Ghost Knife Fish will eat small fish or invertebrates making them incompatible with many schooling tropical fish – thus understanding their social behavior when combined with others forms an essential part of setting up your shared habitat harmoniously which meets everyone’s needs perfectly!
Compatible Tank Mates

For a harmonious environment, suitable tankmates for the Black Ghost Knifefish include peaceful fish such as neon tetras and other larger community species. It’s important to pick tankmates of similar size and temperament in order not to cause harm or stress to the knifefish. Here are a few good picks:
- Geophagus “eartheater” cichlids
- Friendly catfish over 6 inches (15 cm)
- Common plecos
- Silver dollars
- Severums (As long as Severum is solo)
- Bala Sharks
Bad Tank Mates
When introducing tank mates to your Black Ghost Knifefish, it is of great importance to stay away from small fish such as neon tetras and guppies since they can be swallowed by the ghost knifefish which might cause damage or death. It’s necessary for you to choose compatible companions, both in size and nature, so that all inhabitants are kept safe. Here are also some bad fish:
- Aggressive cichlids
- Other Ghost Knife Fish (they are aggressive to their own kind)
- Elephant Noses
- Baby Whales ( Brienomyrus brachyistius )
You may see other blogs and forums state fish like Elephant noses are okay. I will say that fish that generate electrical impulses/current like them will upset fish with similar systems. This is why the Elephant Nose is a bad choice. They usually fight at night too – and you will see the aftermath in the morning!
Common Health Problems
The Black Ghost Knifefish is especially vulnerable to skin ailments such as Ich and other parasitic infestations due to their lack of scales. It’s important for the owners of these fish to be aware of potential health issues in order to ensure its wellbeing.
Apart from diseases , stress can also occur with changes in water temperature, bullying, diet or light exposure which should all be monitored carefully by ghost knifefish keepers so they may address any problems quickly before it causes significant damage.
Preventative Measures
Maintaining optimal water parameters and providing a suitable natural habitat can ensure that your Black Ghost Knifefish stays healthy. It is important to maintain consistency in temperature, pH levels , and salinity, as well as regularly change the tank’s water content.
You should provide them with plenty of hiding places or decorations which simulate their usual environment while also ensuring they receive balanced nutrition without overfeeding them for full health benefits. By taking these precautions, you will create an ideal living space for your ghost knifefish so it remains happy and healthy long-term.
Breeding Challenges and Considerations
Breeding Black Ghost Knifefish in a domestic aquarium is difficult due to Indonesian fisheries’ secret techniques for breeding them. To optimize success, the ideal environment should have a low level of light and sound, along with stable temperatures that necessitate frequent water changes.
When eggs are laid, they may take three days to hatch, at which point feeding infusoria or brine shrimp nauplii as well as powdered fry food would be appropriate nutrition sources for young fish. In any case, when attempting black ghost knifefish reproduction, it is imperative that you always prioritize their welfare above everything else during this process. Below is a quick video of Knife Fish fry ( video source ).
While there are no guarantees on successfully reproducing your own stock of this iconic species, such attempts can yield tremendous rewards if done correctly. Ultimately making all efforts worthwhile when observing beautiful adult specimens swimming happily around an aquascape!
Responsible Breeding Practices
When breeding the Black Ghost Knifefish, you must ensure their tank replicates its natural habitat. Maintain a constant temperature between 78-82°F and provide darkness and peace to create conditions similar to what is experienced in the wild when these fish spawn during the rainy season. Regularly change out some of the water for proper maintenance.
If successful with your efforts, it’s essential that you nurture any fry produced by transferring them into another aquarium kept at an appropriate temperature as well as feeding them live or frozen food options for optimal healthiness and nutrition. By following such practices responsibly, you can contribute greatly to preserving this remarkable species!
Frequently Asked Questions
How much do black ghost knife fish cost?
For a stunning aquarium inhabitant, the black ghost knife fish is an attractive option! This type of fish can generally be purchased for under $25 each when small and provides beautiful display value.
These aquatic creatures are known to have good longevity. They are capable of surviving up to 10 years when given proper care and attention in compatible water conditions that vary from medium-hard waters to soft acidic aquaria. Ghost knives make excellent pet companions due to their peaceful nature as well as how easy it is to look after them overall.
How long do black ghost knife fish take to grow?
Black ghost knife fish can reach up to 24 inches (60 cm) in only two years if they are provided with the right environment and nutrition. This species of fish, when purchased. Measures a couple of inches, but with proper care it can grow quickly into its full size. An ideal tank for them should have at least 100 gallons (113 liters) capacity as well as maintain an optimal temperature range for their growth. With correct conditions met, you will find your black ghost or Ghost Knife Fish reaching maturity within two years!
What fish go well with black ghost knife?
For tankmates for your black ghost knife fish, think about peaceful types such as geophagus cichlids and some other friendly sizable catfish. These kinds of aquatic creatures will certainly bring variety to the aquarium environment while providing much fun!
What is the ghost fish?
A ghost fish is a fish from the knifefish family Apterontidae. They are originally from South America and grow large, with many varieties growing over 18 inches in length. They are generally peaceful, but due to their large size they may smaller fish as they get larger.
How big does a ghost fish get?
The Black Ghost Knifefish is quite an impressive creature when mature, as it can grow up to 20 inches long. If you want to house this species of fish in your home aquarium, then a minimum tank size of 100 gallons must be provided.
Due to the sensitivity that these ghost knifefishes have to changes in water conditions and environmental parameters such as temperature and pH. Close attention should always be paid to their habitat so any alterations are monitored regularly for them to feel comfortable and safe within its living space.
Closing Thoughts
In closing, taking proper care of the Black Ghost Knifefish necessitates understanding its natural habitat and other necessities such as tank requirements, nutrition habits, social behavior and potential health issues. To give them a pleasant home environment that resembles their native setting where they can thrive is essential. This means following all the advice included in this article.
Remember that being responsible when dealing with these extraordinary creatures is key to ensure their optimal wellbeing. As you carry on your journey along side your Black Ghost or Ghost Knifefish companion, make sure it has what it needs so both you enjoy a lovely time together!
Ever kept these tropical freshwater fish before? Let us know your experience with the Black Ghost Knife Fish in the comments below!
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Black Ghost Knife Fish Care Guide: Breeding, Disease, Diet
- By Adam Edmond
Are Black Ghost Knife Fish Lone Or Societal In Nature?
The black ghost knife fish is not social. It has an aggressive nature which does not go well with fish schools. They contact other black ghost knife fish or other species, but they do not mix that frequently. They are more active during the night but prefer to hang around on their own, much like a ghost.
They like to swim around for food, and as long as they have an expanse of freshwater around them, they are happy. Their aggression flashes through when they are confined to tanks too small for their needs. These fishes have poor eyesight, and they do not like to bump into things. The recommended number of black ghost knife fish in the tank is two. Two black ghost knife fish can live in a confined space.

Black Ghost Knife Fish Appearance
There seems to be an endless list of interesting facts about the black ghost knifefish, and we have another one to add to the list . They do not have scales or fins contrary to other fish. Almost like a flying fish or a sting ray, the black ghost knifefish has billowing sides that makes it look like it glides through water. It doesn’t have a caudal or a dorsal fin either and greatly resembles a knife.
Because it doesn’t have scales, the black ghost knifefish is extra tough to care for because they are more susceptible to changes in water parameters and common fish diseases. The source of their electric reception and emission is located on their tails. It’s difficult to sex the black ghost knifefish, but studies have shown that the females have a higher electrical frequency than the males. Further studies have been made to learn more about their development.
Black Ghost Knife Fish Size
How big does a black ghost knife fish get? When they are completely stretched out, the black ghost knifefish can reach up to 20 inches long!

Natural Habitat And Origin
Every fish has a natural habitat and origin environment. The natural habitat of the black ghost knife fish is the Amazonian forest and the Amazon River and its tributaries. The rare ecosystem of the Amazon forest makes this fish a rare, beautiful species. The fish is present in Brazil, Venezuela, Peru, Ecuador, and other countries like Paraguay. The natural habitat of these fish is small rivers and streams with warm waters and cloudy streams. Such waters help the fish activate its electro navigation system with weak electrical currents from its body.
zzThe nocturnal predator fish species of black ghost knife fish is also present in flooded mangrove rivers in the wet season. The fish thrives in the darkest corners of the Amazonian river delta, fostering its nocturnal behavior. The origin of these fishes can be traced back to the freshwater habitats of South America. The fishes grow well in the neutral waters of the Amazon
As you can imagine, the black ghost knifefish is a solid black color with only a few white decorations. The white spots are seen on their tails and their noses.
The color and the markings of the fish body help us identify a black ghost knife fish. The fish has markings on its body instead of being solid-colored ones. The color may not be bright, but it gives an overall unique appearance to the fish. Scales do not cover the body. Instead, it has smooth skin, which gives it a striking appearance. The color of the body is matte black and has around two white spots placed in a strategic location on the body. One of the markings occurs on its tail, and the other is on its nose. Sometimes this mark extends up to its back. Sometimes, the color of the fish is in varying shades of black due to environmental influences.
Lifespan of Black Ghost Knife Fish
If water conditions are maintained to a tee, your black ghost knifefish can live in the aquarium anywhere from 10-15 years!
Feeding Black Ghost Knife Fish
The black ghost knifefish is fierce-looking species that lives on a carnivorous diet. They get a steady supply of insects, larvae, smaller fish and worms in the wild. You should try to simulate this diet as much as possible in captivity. This means you would need regular feedings with bloodworms , brine shrimp and other fresh or frozen foods.
They are not picky eaters, but it could take them a while to get accustomed to fish flakes and pellets. Even when they have become accustomed to this diet, we would still suggest balancing it with regular supplements of live and frozen food. In order to know the exact amount to feed your black ghost knifefish, observe them when feeding. They shouldn’t need more than the amount they can consume within 5 min.
Be sure to feed the black ghost knifefish at night as well, since that is when they would naturally feed. Being nocturnal, you may have to get used to caring for your black ghost knifefish differently. In the beginning when they are first brought home, it will be more difficult to gauge how much to feed them because it will take them a while to come out of hiding and graze.
However, when they finally make the attempt, give them some time and make sure you clear the leftovers from the tank as soon as possible to maintain the integrity of the water. Black ghost knifefish are quite docile when it comes to their owners, and other than being very “pettable”, some aquarists have even trained their fish to feed from their hands. It could take some time and a lot of patience, but this is another option if you experience difficulty getting them to eat.
Black ghost knife fish like to feed on high protein sources. Always try to supply protein sources like worms and insects to the species. Some of the common worms that the black ghost knife fish eats as feed are Bloodworms. They also feed on brine shrimp. Insects like crickets also become the feed of these fishes.
The black ghost knifefish is from the apteronotidae family and is a tropical freshwater fish native to South America.
Black Ghost Knife Fish Care and Tank Setup
Black ghost knife fish tank size and specifications, minimum tank size.
They can grow quite large, and the minimum tank size for a single black ghost knifefish is 100 gallons. As mentioned, they are quite friendly towards other fish in an enclosed space, unless they are other knifefish or ones that resemble them. If placed with another black ghost knife fish, make sure you have a large aquarium adding 80-100 gallons per extra fish. A small aquarium tank will only lead to an increase in its aggression levels. If you have more than one black ghost knife fish, keep them in a large tank where they have ample space to move around. A high-quality filter needs to be installed because the fish is susceptible to many diseases and needs clean water at all times.
Optimum Tank Size For Black Ghost Knife Fish
The optimum tank size for a black ghost knife fish is 100 gallons.
Filter Type
The black ghost knife fish need good quality filters for clean water. Pre-filters and canister filters are good for black ghost knife fish aquariums. A high-quality filter maintains the nitrate and ammonia levels in the water.
Substrate
The substrate needs a good soft substrate because it is a bottom feeder. A coarse substrate will only injure the delicate fish without scales. Instead, choose fine sand or small gravel as a substrate.
How Many Fish In 100 Gallons Tank?
One black ghost knife fish needs at least 80 to 100 gallons of the tank. You can keep more than one fish in a larger tank, but you should not go above two fish. This is because keeping more than two black ghost knife fishes in one tank will cause an overlap of their electric fields, which will confuse them and stress them out.
Black Ghost Knife Fish Tank Maintenance And Care
You need to have adequate experience to handle a black ghost fish. They are extra sensitive to their anatomy, so investing in instruments such as a water filter and UV sterilizer can make your job easier. As you can imagine, the lack of scales makes the ghost fish particularly susceptible to skin diseases such as Ich (which is very common).
Tank Conditions for Black Ghost Knife Fish
The black knife ghostfish can be found all over South America, in the warmer waters of Venezuela all the way to freshwater basins in Peru. If you take a look at the rivers and streams in these areas, you will see that they are full of plants, rocks and places for the fish to dart in and out of.

It’s best to keep the aquarium conditions like so with murkier waters and not a lot of sunlight. In these areas, the water flow is also apparent, but not too aggressive. Since they have a more timid nature and their natural environment is full of these places, make sure you give your black ghost knifefish plenty of places to hide.
Look into plenty of rocks and vegetation. Natural plants are best but if you decide to place artificial ones, make sure that there are no sharp edges in case they injure your black ghost knifefish. The scaleless attribute is a unique one, and requires more consideration when decorating the tank.
Water Parameters For Black Ghost Knife Fish
The black ghost knife fish lives in a varied range of water parameters, making it ideal for living in an aquarium. Although the fish can live in different water parameters, it is quite sensitive to water conditions. The water quality needs to be great and well maintained at all times.
Temperature
They are more accustomed to warm waters, so the temperature for the aquarium should be at 73-82 degrees Fahrenheit (23-28 degrees Celsius).
As for the water conditions, the pH level should be relatively neutral at 6-8 and water hardness of 5-19 dGH.
Water Hardness levels
The hardness level of water for black ghost knife fish is 0 to 10 Kh. To maintain the health of the black ghost knife fish, you have to keep testing the water conditions and create a stable environment. The water flow should also be medium to high current to mimic the riverine habitat. Since the species is fresh water in nature, avoid keeping these fishes in brackish water.
You know they are having skin issues when they start to rub themselves on surfaces around the tank. This signifies that they are itching. Their monochrome color also makes it easy to spot skin abnormalities, so keep a close watch on them.
Luckily, most skin diseases are quite easy to treat, but make sure they are never given copper-based medicine because they cannot handle it.
Black Ghost Knife Fish Tank Landscape
The tank landscape is very important to create a suitable environment for the black ghost knife fish. The fish is predominantly nocturnal and thrives in darkness. Ensure that you provide medium to dim lighting in the tank to mimic their natural habitat. The addition of a soft substrate like fine sand and gravel mix is right for proper tank setup. Keep a lot of hiding places for the fish to stay active.

Best Plants For Black Ghost Knife Fish Tanks
The natural habitat of black ghost knife fish has a lot of flora and greenery. Therefore, the fish in the tank also likes plants in the setup. The tank size is large and has a lot of space to install logs and plants. These also add up as hiding places for the fishes. You can add plants like Dwarf water lettuce, Hornwort, red root floater, etc. Floating plants are great for decorating the black ghost knife fish tank.
Worst Plants For Black Ghost Knife Fish Tanks
The worst plants for the tank will be plants that have a brackish water habitat. Plants that do not grow as sub-water species cannot be put into the tanks.
Decorations For Black Ghost Knife Fish Tanks
There are many decorative pieces that you can put into the tank for the playful black ghost knife fish tanks. For example, you can put a ghost tube in it. A simple plastic tube set can come across as a ghost tube. The ghost tube acts as a hiding place for the fish. This way, the fish will always be visible even when hiding. You can mimic a river bed with your decorations. However, avoid hard rocks in the tankin tank décor.
Lighting For Black Ghost Knife Fish Tanks
The lighting for black ghost knife fish tanks should be muted and dim to mimic their nocturnal environment. The medium and dim lighting helps these beautiful fishes thrive.
Nitrogen Requirement For Black Ghost Knife Fish Tanks
The nitrogen requirement for black ghost knife fish tanks is very low because the fish does not have scales and is very sensitive to water nitrogen levels. You need to install a high-efficiency filter to keep nitrogen optimal in the tank.
Black Ghost Compatibility & Tank Mates
When you introduce a black ghost knife fish to the tank, you must know if it was bred in captivity or captured in the wild. This is because if it’s from the wild, you may need to isolate it for a while before introducing it to the community aquarium. After all, they can transfer foreign bacteria into the tank and perhaps soil the aquarium’s condition.
The black ghost knife fish is generally considered peaceful unless they see other similar fish or other knife fish. When thinking about introducing tank mates, try to opt for ones that are similar in size (not appearance) and temperament. Cichlids can have aggressive breeds (firemouth, green terror), but peaceful ones can make great companions.
Ideal Tank Mates For Black Ghost Knife Fish
Catfish and tetras are good with the black ghost knife fish, but make sure the aquarium mates you add are not small enough to be mistaken for food. Another instance where they can be aggressive is if the tank is too small, so make sure you have a large tank for all the species you plan to keep. A good rule of thumb is to opt for species around 10 inches (a little less is fine) and have a good disposition. Other ideal mates for a black ghost knife fish are Angelfishes , Bichir , Discus , Oscar , Geophagus, etc. A peaceful fish that does not challenge a black ghost knife fish’s space is a good match for black beauty. You can also keep a silver dollar with a black ghost knife fish if you want to make some beautiful contrasts of color in the tank. Choose tropical fishes with the same habitat as the black ghost knife fish for a peaceful tank. Keep fishes of other species but of comparable sizes with the black ghost knife fish.
Bad Tank Mates For Black Ghost Knife Fish
Some fishes are not at all compatible with the black ghost knife fish. The most common example of such fish is small fish. The black ghost knife fish is not a bully, but it will feed on the small fishes in the night. Only when the fish is small can juvenile fishes live with them. Once their predator side is activated, do not keep small fishes in the same tank.
Moreover, black ghost knife fish does not become a part of a mixed aquarium. You may think that it is a riverine species used to other species, but its natural predator streak does not allow other shrimpshrimps snails to live in the same tank. The black ghost knife fish will simply eat the other species. These fishes are best for one fish-only tank.
Compatibility
As another general rule of thumb, do not keep black ghost knife fish with its kind or other similar species if you do not have a large enough tank. We also suggest keeping the maximum at 2 black ghost knife fish and no more than that. If you give them enough space to swim, there will less likely be fights that break out. Larger peaceful fish are the optimal choice.
Breeding Black Ghost Knife Fish
They are very large, making it hard to breed these fish in captivity. Your aquarium will need to be very large to house both a male and a female, and in cases where there have been successful cases of breeding, the methods have been debated. They are mainly bred in commercial facilities (a large one in Indonesia), but little information is known about the process.
A pond is the better alternative to a large aquarium and can simulate the right environment much more easily. If you decide to attempt this difficult breeding, there are some conditions you must adhere to. We would also strongly advise approaching breeding with a level of caution since there is a limited amount of information and rarely any successful cases in captivity.
You need a male and female black ghost fish, which presents the most difficulty. They need to be a bonded pair that you can attempt, but it mostly happens naturally. Then the aquarium or pond comes into question. You need it to be large enough for both, so we are looking at AT LEAST 180 gallons.
This aquarium or pond would need to be in a dimly lit area without direct exposure to sunlight. It should be near a noisy area or one with a lot of foot traffic or movement. As for what goes into the tank, you need to be prepared to populate it with plenty of vegetation and rocks, and other surfaces for them to hide. Much like some other species, these fish are prone to consuming their eggs for food after spawning.
The female won’t spawn if she is stressed or feels as if she might be in danger; this is another reason why it’s so imperative to have enough hiding places in the tank.
You need to have a secure place to place the eggs or remove them. Keeping the water temperature warmer, around 27-28 degrees Celsius, is also recommended. The parents will also need flooding and draining consistently. This aquarium change will signify the wet season in South America and hopefully trigger breeding.
Pond breeding has more of a chance of success compared to aquarium breeding. For sure, you must always keep the conditions at optimal levels as these fish are extra sensitive.
Let’s say you are successful in breeding, and then you should actively remove either the eggs or the parents (the parents being the easier choice). You should see the fry in about 3 days and start with a steady diet consisting of infusoria, then some meat-based meal such as brine shrimp, and they move on the flakes. About a month or two, you can introduce them to a more varied diet when they are old enough.
Black Ghost Knife Fish Breeding Levels
Black ghost knife fish sexual dimorphism .
The black ghost knife fish is difficult to distinguish based on gender. It is not easy to differentiate the male from the female based on the external marks and features. You cannot identify their genders at home. However, a way to identify is to look for their eyes. The male black ghost knife fish has eyes on the top of its head. The female black ghost knife fish has eyes on the front of its head. Even though you identify their genders, breeding a pair of black ghost knife fish is always a gamble. You have to keep the aquarium very dark for the breeding to happen successfully. This is why pond breeding is more successful than aquarium breeding.
Black Ghost Knife Fish Tanks Common Diseases And Treatments

The black ghost knife fish is very susceptible to diseases. This is because the fish lacks scales and mottled skin for protection that other fishes have. Therefore, even the smallest of injuries can lead to bacterial infections like Ich. Ich is a common disease in other freshwater fishes. The disease manifests as white spots and patches on the fish’s body. The treatment of Ich is very easy if it is done at the right time. Removing the stress factor and improving the water quality often work better than any other treatment. Sometimes, sulfur-based liquid medications added in the tank also help improve the condition of the fish. Another way is to raise the temperature of the water slightly. Since black ghost knife fish lives in warm waters, it will provide a bit of relief to them.
Facts About Black Ghost Knife Fish
- Also known as Black Knife in short
- Amazonian tribes believe these fishes hold the spirits of the dead
- They live in fresh tropical water
- Have smooth black matte skin without scales
- Need moderate care level
- They are not social fishes and need space
- Live a long life of about 15 years.
Are Black Ghost Knife Fish Right For You?
If you are enthusiastic about keeping rare fishes, the black ghost knife fish is a great pick. However, this is not the right species if you want to keep a mixed aquarium. Choose this black beauty any day if you want a lone pair of fish for company. The fish is carnivorous, so it needs special attention. The fish also needs clean, optimal conditions in its environment for a healthy life. If you are ready to fulfill these conditions, the black ghost knife fish is good.
Is The Black Ghost Knife Fish Aggressive?
No, the black ghost knife fish is not completely aggressive. It is a natural predator, but it is only aggressive in a tank when there are other knife fishes in it. Therefore, it is advised to only keep one of these large fishes or a maximum of two in a large tank.
Is It Difficult To Keep The Black Ghost Knife Fish In A Tank?
No, as long as the tank size is large and the black ghost knife fish has enough space to itself, it is not difficult to keep the fish in the tank. Keeping a black ghost knife fish as a pet is very easy once you get used to it.
Can I Give Plant Pellets To The Black Ghost Knife Fish?
The black ghost knife fish is a carnivorous fish that feeds on small insects, larvae, and shrimp. You can give these as feed to the black ghost knife fish. You can also feed the Fish some pellets occasionally, but make sure the pellets are specifically formulated for carnivorous fishes. Plant pellets are not a good option for the Fish.
Is The Black Ghost Knife Fish A Bottom Feeder?
Yes, the Fish usually stays near to the substrate or small foliage, especially during the day. It prefers to eat near the bottom and becomes more active at night. They only come up during the day if you have enough foliage on top for shade, as the Fish is a very private animal.
In What Time Period Does A Black Ghost Knife Fish Reach Its Full Size?
The black ghost knife is a large fish that reaches its full size in a matter of nearly two years. You have to take special care of its nutritional needs during the growing period.
Due to their eye-catching and unique appearance, the black ghost knifefish is an immensely popular fish in the aquarium trade. However, their beauty isn’t without a price as it also takes extra effort to care for these fish. Their temperament is one thing that doesn’t cause any problems because they are very friendly – until they meet their kind.
Other black ghost knifefish and similar-looking species can set them off, especially if your tank isn’t large enough. Due to them being scaleless fish, you also need to be extra careful about what you place in the tank. This lack of protection is precisely what makes them extra sensitive to diseases. On the bright side, the black ghost knifefish is single-colored, making it easy to spot potential issues.
Other unique traits of this fish are their electrosensory organ and being nocturnal. They have poor vision and rely on the emission and reception of these electric signals to map out their surroundings and communicate. As an aquarist and keeper of the black ghost knife fish, you need to make sure you do all your feeding (a carnivorous diet) and other interactions at night.
They are amazing additions to your tank and are trainable fish. With enough patience and time, it’s more than possible to be able to pet these fish and have them eat out of your palm.
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Black Ghost Knife Fish (Apteronotus albifrons): Care Guide

Table of Contents
The Black Ghost Knife Fish ( Apteronotus albifrons ) is an interesting aquarium fish that originates in South America. They have a long body that is shaped like a knife. They will grow to a significant size, but they are agile fish that are able to maneuver around objects in the tank. They will also live a long time if they are well cared for. As a nocturnal fish, they will feed primarily at night. These fish are known to have poor vision, but they possess an electrical organ that helps them locate their food. An organ in its tail is responsible for generating electrical energy.
These fish are found in the tropical waters of the Amazon River Basin of South America. Among some of the tribes of the Amazonian jungles, it is believed that the souls of the deceased inhabit these fish.
Black Ghost Knife Fish Care
Black Ghost Knife Fish are moderately difficult fish to take care of. They are fish that grow to a significant size, and they do not tolerate poor water quality. Therefore, a proper tank setup and regular maintenance are important. These fish aren’t reserved for experts only but require more attention and care than other hardier fish in the aquarium hobby.
Another factor to consider is that these fish do not have scales. This makes them susceptible to injuries and infections. Therefore, installing a UV sterilizer in the tank may be wise. One thing to remember about these fish is that copper-based treatments are extremely poisonous to them. If copper-based treatment is administered, the fish may begin to scratch and rub themselves around the tank. There are other proper methods of treating an infection for these fish. With early treatment and an increase in temperature (approximately 86°F), there is a good chance they can fight off the infection.
Black Ghost Knife fish are nocturnal, meaning they are most active at night and sleep throughout the day. Although they have poor eyesight, they are able to search and converse using an electromagnetic field.
They are shy fish, especially when introduced to a new habitat. After settling into the new habitat, they will emerge from their hiding location overnight and swim near the base of leafy plants and other vegetation.
While they can be shy fish, remember that if they are kept with other knife fish, they can become violent and aggressive.
Apart from two white rings on its tail and a white stripe on its nose that often runs along its back, the Black Ghost Knife fish is completely black. It has no caudal or dorsal fins. Hence it has the appearance of a knife.
There are no scales on this knife fish species. Its smooth long body is part of what makes this fish so unique.
The Black Ghost Knife Fish is native to the Amazon River and its tributaries. They can be found in the Amazon River, passing through Venezuela, Paraguay, and all the way down to Peru’s freshwater basins. The river is the perfect habitat for these fish since there are plenty of hiding places between driftwood, rocks, and dense vegetation. The water can be very muddy, have currents, and have poor lighting.
In their native habitat, the water would be warm, with a pH close to neutral.
Temperature
The tank’s water temperature must be maintained at a constant level between 73-82°F (23-28°C).
Water pH & Water Parameters
The pH range for the Black Ghost Knife fish is 6.0 to 8.0, with water hardness ranging from 5 to 19 dGH.
It is important to note that freshwater fish cannot survive in brackish water.
This river-dwelling species prefers water with a moderate to high current.
Black Ghost Knife Fish Size
The Black Ghost Knife Fish is one of the largest ghost knife fish species. On average, the black ghost knife fish grows 19 inches (50 cm) long, while some grow 23 inches (60 cm) long.
The minimum tank size for one Black Ghost Knife Fish is 100 gallons. Since they are large fish, a large tank is needed to accommodate their size.
Keeping the fish in a tank may cause the fish to become overly aggressive and also cause health issues for the fish. Since the aquarium would be the foundation of their habitat, it is important that the fish is housed in a proper-sized tank.
Food & Diet
Black Ghost Knife Fish require a carnivorous diet of live or frozen foods. Bloodworms, prawns, brine shrimp, and tubifex are some of their favorite foods.
They are known for having difficulty adapting to dry flake and pellet foods.
Feeding them a protein-rich diet similar to what they feed in their native environment is the key to their longevity. In short, the key is to feed them what they desire, at least to some extent.
In the wild, Black Ghost Knife Fish are considered micro-predators of insect larvae.
The Black Ghost Knife fish lives for a very long time. It can survive for up to 15 years if properly looked for.
Black Ghost Knifefish grow large but aren’t the most aggressive fish species. Therefore, many species of fish are suitable as their tank mates.
Here’s a list of potentially suitable tank mates for Black Ghost Knifefish:
- Silver Dollar Fish
- Electric Blue Acara
- Bristlenose Pleco
- Corydoras Catfish
- Dinosaur Bichir
- African Rope Fish
- Saddled Bichir
- Sailfin Molly
- Green Swordtail
- Balloon Molly
- Glass Catfish
- Pictus Catfish
- Severum Cichlid
Since Black Ghost Knifefish aren’t particularly aggressive species, it should not be too difficult to find suitable tank mates for them.
As juveniles, Black Ghost Knifefish can be kept in the same tank with smaller aquarium fish such as tetras and danios. Some fishkeepers have successfully kept juvenile Black Ghost Knifefish with small fish such as Neon Tetras, Green Neon Tetras, Celestial Peral Danios, and Zebra Danios. However, keeping fully grown Black Ghost Knifefish with significantly smaller fish is not recommended since they may try to eat them.
Are Black Ghost Knife Fish Aggressive?
Despite their large size, Black Ghost Knife Fish are not particularly aggressive. In fact, they tend to be peaceful fish that keep to themselves.
That said, when Black Ghost Knifefish are kept in aquariums that are too small, it can trigger aggressive behavior. Therefore, providing a tank size of at least 100 gallons is important.
If adequate space is provided, and they are kept with other peaceful fish of similar size, there should be little risk compatibility issues.
A tank setup for Black Ghost Knifefish should have medium to low lighting, plenty of hiding places, and open spaces to allow them to swim freely.
Regarding the lighting requirement, Black Ghost Knifefish are native to environments with limited lighting. Their limited eyesight and enhanced electric receptors are signs of their adaptation to such low-light environments. When setting up a low-light tank, consider its effect on other tank mates and the overall setup. For example, aquarium plants that require strong light may not be suitable.
Regarding the hiding places, this can be created with a combination of hardscapes and low-light aquarium plants. Hardscapes such as rocks and driftwood would be great since they would mimic their natural environment. Remember that Black Ghost Knifefish do not have scales, and sharp objects can easily injure them.
If you have rocks, driftwood, and other hardscapes that may be sharp or too rough, you can cover them with Java moss . Java moss are low-light plants, so they will be suitable aquarium plants in their tank.
Another great option is Java fern . This is another aquarium plant that thrives in low-light environments. Java fern has large overhanging leaves, which will help provide cover and a sense of security for the fish.
Regarding the aquarium substrate, smooth gravel or sand is recommended. Sharp or overly rough substrates should be avoided since they can cause injury to the scale-less Black Ghost Knifefish.
Do Black Ghost Knife Fish require a hiding tube?
A hiding tube for Black Ghost Knife Fish is not required, but it is highly recommended.
Of course, if the tank is set up with plenty of hiding places, the Black Ghost Knife Fish can find cover elsewhere. However, the hiding tube provides a snug hiding spot that is often difficult to replicate with natural rocks and driftwood.
Another advantage of a hiding tube is the fact that it is clear, allowing the fishkeeper to view the fish even when it is in hiding. Since they can spend long hours in hiding, this can make a significant difference to the fishkeeper. Even though it is clear and visible from the outside, the Black Ghost Knife Fish will still feel safe, based on senses from their electroreceptors.
What does the Black Ghost Knife Fish habitat look like in the wild?
Black Ghost Knife Fish are native to the upper basin of the Amazon River in South America.
The water current is usually fast-flowing, and the river can be deep. While most fish species prefer calm waters, Black Ghost Knife Fish would be the exception. It can thrive in rivers with relatively strong currents.
The river usually consists of a sandy floor.
Since this is a tropical environment, the water temperature remains relatively warm, averaging mid 80’s (Fahrenheit).
Black Ghost Knife Fish are egg spawners, and they are known to spawn during the rainy season.
Most spawns occur during the night (11 pm – 2 am). This makes sense since they are nocturnal fish.
A pair of one male and one female would spawn in areas of dense vegetation. The eggs typically hatch within a week of spawning, and the parents will not look after the fry.
How to Breed Black Ghost Knife Fish
Breeding Black Ghost Knife Fish is considered to be difficult, but it is possible. They have been bred in captivity and are currently being bred commercially for the ornamental fish trade.
In order to breed Black Ghost Knife Fish, place a breeding pair in a very large tank or pond. A breeding pair would require a minimum tank size of 200 gallons. Unfortunately, this requirement can make it difficult for the average hobbyist to breed this fish.
The breeding pair must be mature enough to breed. Black Ghost Knife Fish reach sexual maturity at 1.5-2 years, so this would be considered the minimum.
In addition, the male and female must be compatible in order to mate. Not all pairs are compatible and will show aggression towards each other instead of mating. In order to successfully find a mating pair, multiple attempts of pairing males and females may be required.
An alternative to choosing a mating pair is to allow the Black Ghost Knife Fish to choose their mates on their own. Of course, housing a group of fish would require a very large tank. However, if this is an option, this may result in a higher chance of success.
When multiple males are present, they will compete against each other. The males will act aggressively and try to drive the other males away from the female. The female will select a single male to spawn at night. According to a study published in the Indonesian Aquaculture Journal , a spawning ratio of two males and three females may achieve better reproductive performance. However, further research may be required before concluding on the best spawning ratio.
In order to induce spawning, maintaining good water quality is important. Daily water changes of up to 60% may help induce spawning behavior. Some aquaculture farms may administer hormones to help induce spawning as well.
After a spawn, the adults may eat the eggs. Therefore, covering the ground with large gravel may help. The eggs would fall between the gravel, preventing them from getting eaten. After a spawn, the eggs can be collected manually as well. The eggs should hatch within 3 days to a week.
Similar to the adults, the fry are also carnivorous. Feed them protein-rich foods such as small worms and pellets. Since they may be reluctant to eat during the day, it is best to feed them after dark.
Male or Female
Distinguishing between male and female Black Ghost Knife Fish can be challenging since they have very few differences. The few differences they have are rather subtle, but here are some of their differences:
- Males tend to have eyes positioned more toward the top of their heads than females.
- Females tend to have eyes positioned more towards the front of their heads than males.
- Males tend to be skinnier, and females have a fuller body.
- Females produce higher electric organ discharge (EOD) at a higher frequency than males.
Black Ghost Knife Fish are susceptible to diseases such as fin rot, ich, fungal infections, bacterial infections, and parasites.
Many of the diseases that the Black Ghost Knife Fish are susceptible to aren’t rare. In fact, many of them are diseases that would impact many other freshwater fish.
However, do keep in mind that Black Ghost Knife Fish do not have scales. Therefore, they may be more susceptible to these diseases than other fish that are protected by their scales.
Due to their lack of scales, they are significantly more susceptible to injury from sharp objects. Therefore, it is important to handle them with care and avoid keeping sharp objects in the tank.
Are Black Ghost Knife Fish Blind?
Black Ghost Knife Fish have poor eyesight but are not completely blind. Even though they don’t have strong eyesight, this is rarely a problem since they use their electric organ and receptors to sense their surroundings. Since they are most active during the night and often forage in murky waters, their electrolocation abilities are more useful than their eyesight.
Do Black Ghost Knife Fish produce electric shock?
Black Ghost Knife Fish does have the ability to produce and sense electric impulses. However, it is not strong enough to shock or stun other fish. The electric impulses are mainly used for electrolocation and communication.
Their electric discharge organs (EODs) are useful while they hunt for insect larvae. However, once again, the electric impulses are not used to shock or stun their prey. It is used to locate them.
They possess electromotor and electrosensory organs but are considered only weakly electric fish. In fact, the electric impulses are often undetectable by other fish.
How do Black Ghost Knife Fish sleep?
Black ghost knifefish sleep during the day, often nestled in crevices of rocks, driftwood, or dense vegetation. Aquatic plants with large leaves, such as Java Fern and Amazon Sword will provide plenty of cover for the fish, giving them a sense of security while they sleep. Keep in mind that these fish can be timid, so the cover will be beneficial to them.
In an aquarium environment, if you provide them a hiding tube, they will most likely sleep in there during the day.
Do Black Ghost Knife Fish have teeth?
Black Ghost Knife Fish do not have teeth, but they do have a beak-like structure.
About The Author
Fish Laboratory
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Black Ghost Knife Fish: A Definitive Guide For Aquarists
- June 18, 2022

Table of Contents Show
Overview of the black ghost knife fish, appearance and size, food and diet, tank setup and size, water parameters, behavior and temperament, compatibility and tank mates, common diseases, how long do black ghost knifefish take to grow, how can you tell if a black ghost fish is male or female, will a black ghost knife eat snails, can ghost knife fish live with cichlids, does ghost knife need air pump, final thoughts.
The black ghost knife fish has gotten a lot of attention in the fishkeeping community. It is interesting as it is unique, and it has caught my eyes. It is one of the freshwater species that amazes me for its astounding features I don’t see every day in other fishes.
This fish has a unique appearance, so there’s no doubt that it has captured the interest of a lot of fishkeeping enthusiasts, too. When it’s well taken care of, it can grow and reach up to one foot and stay healthy.
In this guide, we’ll discuss everything to know about keeping this fish. Information will include their diet, tank size, and more!
If well maintained and taken care of, you can expect your ghost to live well over a decade.
We’ll talk more about this later. For now, let’s get to the overview of what you need to know about the ghost.
The black ghost (Apteronotus albifrons) isn’t as straightforward to care for when compared to other species due to its unique needs aside from its large size.
They’re nocturnal fishes native to South America. The fish has poor eyesight, but they can use electrical signals to move around and feel their surroundings.
Their electric receptors won’t stun you, though. Instead, they help the BGK in finding their food.
They are commonly found in rivers of Paraguay and Parana, so they are in countries like Brazil, Venezuela, Argentina, and Paraguay.
Their natural habitat is full of vegetation and is characterized with a lot of crannies and nooks for hiding. The water has moderate currents and murky with low lighting.
The water in their natural habitat can also be warm with neutral pH.
On the other hand, the substrate in their natural habitat is soft sand; thus, it won’t scratch or harm the skin of the BGK. This is very important because the fish is scaleless.
They are not the only dwellers in the rivers mentioned earlier but also a lot of insects, which are food to our featured fish. They also feed on insect larvae.
To successfully keep a knife fish black ghost in captivity, the tank should resemble their natural habitat.
Their common name is knifefish, primarily due to the absence of a caudal or a dorsal fin, making it appear like a blade.
The “black knife” in its name is due to their resemblance to a blade, while “ghost” comes from the belief that ghosts of dead people are in their body.
Instead of a dorsal or caudal fin, it has an anal fin. It is distinctively running along its body’s bottom edges and then rippling back and forth.
For this distinct characteristic, the BGK can easily move around even in tight spaces.
Unlike cute bettas and guppies, the black ghost knife (BGK) is a relatively large pet, so a lot of swimming and living space must be considered.
Considered a bony fish, they belong to the knifefish group and a member of the Apteronotidae family .
The fish is unique for the electrical organ in their caudal peduncles that they use to find food. This fish requires at least a 150-gallon tank along with a great filtration system.
They’re also reclusive and timid and require a lot of hiding places. That is why you must consider adding more rocks and roots in the tank.
Use fine gravel for fine substrate and subdued to dark lighting for its lights.
Some people may also prefer buying a ghost tube for their ghost fish. This is a plastic tube that aids in viewing at daytime.
Once the fish has become familiar with the tank and their surroundings, they can be trusting and tame. Some hobbyists even claim holding them in their hands.
The ghost can live with a community fish provided you combine them with peaceful and larger species. However, they tend to be aggressive towards fishes of the same size as them. They aren’t as friendly to fish of smaller sizes either.
For their diet, the BGK can feed on all types of live food, such as chopped earthworms, meat, and frozen/flaked foods.
Over the years, the fish has been growing in popularity because their appearance stands out. A lot of them are now captive-bred and available at affordable prices ranging from $15 to $20 depending on their size.
In aquarium specialty stores, you might find them in overcrowded tanks. For this reason, check what you’re buying and ensure you’re getting a healthy ghost black knife fish. Look for the white spots on the tail of the fish.
A well taken care of black knife ghost fish can live for about 10 years or sometimes even more when kept in optimal conditions. Some even claim that they can reach up to 15 years.
A few things to remember if you want your fish to have a long lifespan is to take care of them properly, including in regards to their food and diet, tank size, and tank setup.
There’s nothing that looks quite like this fish, so you’ll be fascinated seeing it in person.
Intriguingly, they look like a knife, hence the name. They have a long and thin body that has a slight curve in it.
The fish doesn’t have a caudal or dorsal fin. There is simply a thin ridge on top of their body and on their tail is the absence of a caudal fin. They have a skinny tail that has some white bands.
The fish can generate momentum from their anal fins and pectoral fins due to the lack of caudal fin, allowing them to move gracefully.
You can compare the movement of their anal to the stingray’s wings. They can create a wave-like effect, giving them that impressive mobility even with poor eyesight.
For their color, the fish looks almost black. They have a ridge starting at their head running through their back, which is white in color sometimes, and they have white rings or bands on their tail.
For their size, they can grow up to 20 inches, making them not suitable for nano tanks. They need at least 120 gallons of water to thrive and survive in the tank. They have an elongated body, which can make it hard to swim in tight spaces.
The black ghost knife fish can be picky eaters and can have a hard time transitioning to pellet or flake food.
The recommended diet for this big fish should somehow be like what they’re eating in the wild.
Feed them with a natural and protein-rich diet to extend their lifespan and make them happy.
A variety of foods is recommended for your black ghost.
From what I’ve noticed, the fish love a combination of foods, such as frozen and live foods. Prawns, bloodworms, Tubifex, and brine shrimp, are great choices, too.
They don’t have any inclination on flake food, but they do eat carnivore pellets from time to time.
Consider adding feeder fish in their diet, only when your pet is large enough.
This fish is nocturnal, so they look for food at night. As time goes by, the fish will feel at ease to look for food during the daytime.
Consider adding a lighting system that allows subdued and moonlight settings, encouraging the black ghost to come out during times when you need to feed them.
Interestingly, they can also feed from their owner’s hand. Thus, you should keep your hands free from soap and dirt before handling the black ghost.
Feed them once a day, preferably in the evening if this works on your schedule. Alternatively, you can also offer them food several times daily.
Avoid overfeeding your fish because it can make them fat, and it’s not good. Being fat will make them more susceptible to disease aside from putting more waste into the tank.
Know that this fish is sensitive to poor water quality, too.
Reduce the quantity of the food you’re giving them if they can’t eat all of them in a couple of minutes.
The black ghost requires at least 120 gallons of water because they can grow large; thus, they need a tank that can provide them with enough space.
Otherwise, they might show aggression if kept in a smaller tank. It can also affect their health and cause them stress.
The tank size is as important as water quality when it comes to taking care of the ghost. If you’re looking to add another black ghost in the tank, you should also increase the water.
For every extra fish, you should add between 80 and 100 gallons of water. This will help reduce their aggression towards one another.
These fish are sensitive to water changes and conditions like other scaleless fish. You should invest in a high-quality filtration system with a strong flow.
To keep the water clean, you must make partial water changes of between 30 and 50 percent. It will depend on your tank’s bioload.
Water testing is also important to monitor the changes and fluctuations in both nitrate and ammonia levels. And again, it will help to install a UV sterilizer, which can aid in killing any potential bacteria that might cause sickness to your fish.
Most of the time, they spend their time near the tank’s bottom, so using fine gravel and sand mix is also recommended for a substrate. This can mimic the natural environment where they live in the wild.
You must also set up your tank with thick planting around its perimeters. Consider smooth rocks and driftwood for decoration. They don’t generally eat plants, but they love hiding during the daytime.
The fish is rather flexible when it comes to water parameters provided that it is clean. The water temperature should be kept between 73 degrees to 80 degrees Fahrenheit and with water pH level between 6.5 and 8. For the water hardness, it must be between 0 to 10 KH.
But even if they’re quite flexible, you should know that they can be sensitive if kept in a tank with suboptimal water conditions. They can be quite delicate to tolerate average water quality unlike other species.
Without even saying, you must pay close attention to the water quality and take it seriously if you want to keep the black ghost, which can easily catch disease. Do not keep them in a tank with poor water quality.
Aside from the clean water, you must consider the water parameters, which you must keep at optimal levels and stable all the time. If you notice a shift, you should start fixing it.
You might want to buy a water test kit, which will help you check and monitor water quality and parameters. Read reviews to look for the right kit that can return accurate results. This will help you decide better when treating the tank’s water condition.
The fish is less sociable and prefers to do things on their own. As much as possible, they want to be alone and just want to swim in and out of their hiding places to look for food when the sun sets off in the wild.
But then, they can also be aggressive especially when facing or around another fish of its own. You don’t have to worry, though, because you can still keep at least two fishes of the same kind in a single tank.
Generally, they will be just fine provided you give them enough space even if you keep at least two black ghosts in the tank. This will reduce their aggression and territorial behavior.
They’ll just be stressed when kept in a small space. This can also lead to their loneliness.
You’ll also have plenty of choices when it comes to tank mates you can combine with them. The knifefish doesn’t use its size to bully or harass other fishes.
You can consider adding some peaceful fishes provided that they’re quite large.
Some hobbyists have tried pairing them with small fishes like neon tetras and celestial pearl danios. However, this can only be possible if the knifefish is still in its juvenile stage.
A few choices on compatible tank mates with the black ghostinclude the silver dollar fish, rope fish, Oscar fish (provided they’re given enough space), cory catfish, electric blue acara, and bichir.
There are more compatible tank mates to choose from, but these are pretty nice additions to a tank with the ghost black knife fish.
If you want to keep them with similar species, I recommend not going beyond two per tank. Otherwise, aggression is more likely even if you house them in a bigger tank.
The reason for this is that they have poor eyesight and crowding more than two might make them bump into each other when finding food.
It can be quite difficult to breed this fish, and it is not recommended especially for beginners.
On the web, you might find a lot of misinformation regarding this matter, and this includes information of different breeding methods. It can be hard to figure out what will work and what will not.
There are claims that some fisheries in Indonesia were able to breed the black ghost; however, not much has been disclosed about the methods they used. Thus, breeding of the BGK is still a mystery to a lot of aquarists.
A few factors that may encourage breeding are a densely planted aquarium , at least 100 gallons of water, more hiding places, flooding and draining the tank, and eggs being laid in a sheltered area like a cave.
Nevertheless, the black ghost knifefish is not a common fish for breeding in tanks even if there were hobbyists claiming to have successfully done it.
Until more reliable information on breeding the black ghost becomes available, I don’t recommend breeding them.
The fish tends to catch a skin disease when living in a tank with poor water parameters and quality. One of the reasons for this is that they don’t have scales to protect them from the pollutants in the surroundings compared to other fishes.
Ich is a pretty common disease to watch out for. Some signs include white spots, which you can easily recognize due to their black skin color. They might also exhibit a change in behavior.
The fish can also contract infection if their skin gets scratched or cut.
Do you notice cuts in the skin of your fish? Notice behavioral or physical symptoms and take them seriously to reduce the chances of your fish from getting serious infection.
You must ensure that they’re healing correctly and look for treatment options if not.
To prevent a skin infection, inspect the fish for a few minutes daily.
The disease can be treated with an over-the-counter medication. Remember not to use medication with copper. You can also treat it effectively through raising the temperature in the aquarium to 82 degrees Fahrenheit for four days.
Treat the whole tank once ich is active in the tank. You don’t need to isolate your fish, but to treat the water to kill the parasite causing it. When you have controlled it, perform a water change and then reduce the temperature of the water to its usual level.
Knifefish can also be prone to worm infestations and protozoa and skin flukes. They can also be susceptible to other bacterial infections due to injuries.
To be safe, quarantine a new fish before adding it to a tank. This applies for all types of fish you wish to keep, especially if you already have a tank previously setup, allowing you to monitor any potential issues before introducing the fish to your tank.
It may also help to treat the water in your tank using an antibacterial product to kill any disease that a new fish may have.
Frequently Asked Questions
The black ghost knifefish can take about two years to grow to their maximum size. Initially, their small size can be about two inches or five centimeters.
However, they can grow large for up to 60 centimeters or 24 inches and live at least 20 years when kept under optimal conditions.
There isn’t much known about this aspect, but according to sources, males have eyes that are positioned more towards the top of their heads. The females’ eyes can be closer to the front of their head. Both males and females are also said to have glowy red tails during the courting stage.
Yes, a black ghost may eat snails. In the wild, the ghost usually hunts for food after sunset. They are carnivores and can feed on insect larvae, insects, snails, worms, and invertebrates.
Even if the ghost knife fish is a semi-aggressive type of fish species, they can live well with other fishes in a community. Generally, they’re perfect to combine with catfish, cichlids, and other peaceful similar sized fishes.
Yes, they need an air pump because they consume much oxygen from the water. Thus, it is important to aerate and oxygenate your tank’s water.
Is the black ghost knife fish for you? After reading this guide, it’s time to reflect and ask some questions. Can you set up a large tank? Can you keep up with the water parameters and water quality demands of this fish?
You should figure things out before deciding to buy a BGK, which is not for beginners undoubtedly. But then, if you’re an aquarist who has been in the hobby for quite some time and you think you’re ready for the black ghost, there is no stopping you.
Start investing in the right items to include in your tank, including a water filtration system, lighting system, and UV sterilizer, to name some. You must also invest in a high-quality tank of at least 100 gallons in water capacity.
Nevertheless, don’t rush and study your options carefully before deciding to keep a knifefish. Learn more about the ghost and figure out if this is the right pet fish for you. Happy fishkeeping!
Edwin is a passionate fishkeeper since he was a kid. He loves caring for the fish and sharing his ideas about fishkeeping with family and friends. He is the owner of Fishkeeping Adventure.
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Black Ghost Knifefish

The Black Ghost Knifefish is the most well known species of knife fish in the aquarium industry!
The Black Ghost Knifefish Apteronotus albifrons is the most popular knife fish. One reason for this is that they have been imported for decades. Other reasons include being unusual, interesting and amazingly beautiful.
It is readily distinguished from other knife fish by the white and black banded area on the caudal puduncle. It also differs from the Brown Ghost Knife Fish, also called the Long-nosed Black Ghost, because of its shorter snout and the Brown Ghost has only one small white band close to the end of its tail.
This fish is also simply known as a Black Ghost. It is a member of the Apteronotidae Family of ‘ghost knifefish’. These knifefish received their unusual name because of a rumor that some tribes in the Amazon jungle believe that the souls of the dead inhabit these fish. No one can substantiate this information. It may just be a story created by the people collecting the fish, but it’s a good story!
Though it can get quite big, reaching up to around 20 inches (50 cm), this is a very handsome fish. Like other knife fish, the Black Ghost Knife Fish has a flat elongated body. It has a continuously undulating fin along the underside formed by a joining of the caudal and anal fin. Although it may appear clumsy, it has a built in ‘radar’ system that uses low voltage electricity to help it navigate. This radar system and the undulating lower fin allow it to gracefully move forwards and backwards through the aquarium.
These fish can be shy initially, but once acclimated to a new home they will generally come out to feed. Some have even been know to take food right from their owner’s hand. This is a peaceful fish and will not disturb its tank mates. The Black Ghost Knifefish is somewhat sensitive to changes in the water conditions. It is also a big animal that as an adult it will require a large home of 100 gallons or more. But with its good looks and friendly disposition, this knifefish is a distinctive attraction in a large community aquarium.
Until a few years ago, all offered for sale were wild caught and had been imported from South America, mainly from Brazil. The good news is that they are now being bred in Indonesia by the thousands, so much of the pressure has been taken off the wild populations. Odds are that if you see an individual of 5 inches or more offered of sale, it was collected in the wild. Specimens smaller than 5 inches were most likely produced in and imported from Indonesia.
For Information on keeping freshwater fish, see: Freshwater Aquarium Guide: Aquarium Setup and Care
Nice fish and nice aquarium! The video follows a young black Ghost Knife Fish as it surveys the various areas of its aquarium and meets its fellow tankmates while in search for food. There are quite a few awesome shots of both sides of the fish as it swims around and the video does a great job showing what this fish is like on a day to day basis.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Gymnotiformes (Knifefishes)
- Family: Apteronotidae (Ghost Knife Fishes)
- Genus: Apteronotus
- Species: albifrons
- Aquarist Experience Level: Intermediate
- Size of fish – inches: 20.0 inches (50.80 cm)
- Minimum Tank Size: 100 gal (379 L)
- Temperament: Semi-aggressive
- Aquarium Hardiness: Moderately Difficult
- Temperature: 73.0 to 82.0° F (22.8 to 27.8° C)
- My Aquarium – Enter your aquarium to see if this fish is compatible!
- Beginner Fish – Freshwater fish for beginners
- Community Fish – Peaceful Freshwater fish
- Hardy Fish – Hardy Freshwater fish
- Similar size fish – Fish that are 1 inch bigger or smaller
- Coldwater Fish – Looking for cold water fish? (65 °)
Habitat: Distribution / Background
The Black Ghost Knifefish Apteronotus albifrons was described by Linnaeus in 1766. They are found in South America throughout much of the Amazon River and its tributaries. The species is not listed on the IUCN Red List. Other common names they are known by are Black Ghost and Black Ghost Knife Fish.
This knife fish lives in swift moving sandy rivers and migrates to flooded forests during the wet season. Like most Knife fish they like heavily vegetated areas with a lot of hiding places. Their natural habitat is normally pretty dark and these fish have poor vision, so they use an organ that produces an electric field around themselves that will detect objects and movements around it. It helps with navigating and hunting and they also use this unique electrical field as a way to communicate with other knife fish. They are nocturnal and prey on insect larvae, insects, worms and small fish.
- Scientific Name: Apteronotus albifrons
- Social Grouping: Solitary
- IUCN Red List: NE – Not Evaluated or not listed
Description
The Black Ghost can reach up to around 20 inches (50 cm) and has a lifespan of 15 years. Its body is flat and elongated. The caudal peduncle gets very thin, almost ‘rod-like’. It has a continuous fin along the underside formed by a joining of the caudal and anal fin and moves with an undulating motion. Although they appear clumsy, they have a built in ‘radar’ system that uses low voltage electricity to help them navigate. This and their undulating lower fin allow them to gracefully move forwards and backwards through the aquarium.
True to its name, it has a black body, though occasionally there is a white stripe starting from the tip of its nose and running along the top of its back. It has a broad whitish band just in front of the caudal fin (tail fin) and another narrower white band just before the tip of the tail.
- Lifespan: 15 years
Fish Keeping Difficulty
This knife fish is really best for an aquarist with some fish keeping experience. The Black Ghost is a scaleless fish and and can be more prone to disease. Because of the lack of scales they are extremely sensitive to a lot of medications such as cooper. Those that are wild caught can carry parasites. It is highly recommended to have a UV sterilizer in the tank, this will aid in killing many diseases that the knife can get. They are very sensitive to water condition changes as well.
As with many knife fish they are very shy when they are introduced to the tank. It can take time to get them to eat what they need. Being nocturnal by nature makes it even more of an issue and feeding at night may be necessary.
Foods and Feeding
The Black Ghost Knifefish are carnivores . In the wild they are nocturnal, when the sun sets and throughout the night they feed on insect larvae, insects, worms and small fish. In the aquarium this is a fish that prefers fresh or fresh frozen foods such as bloodworms, brine shrimp or blackworms.
Once acclimated to their new home, they should come out of hiding at feeding time. Some have even been taught to feed from their keeper’s hand. These fish are known to create such a bond with their owners that they will eventually lay in their owners hand and eat. Make sure to have no soaps or perfumes on your hands if you do this and sanitize before handling the fish.
- Diet Type: Carnivore
- Flake Food: No
- Tablet / Pellet: Yes
- Live foods (fishes, shrimps, worms): Most of Diet
- Meaty Food: All of Diet
- Feeding Frequency: Daily – When acclimating the Black Ghost Knifefish, offering it several feedings a day can help it get comfortable with coming out more.
Aquarium Care
This fish is scaleless and as with most scaleless fish, it is very sensitive to water condition changes. A high quality filter is a must. Weekly water changes of 30 – 50% are needed, depending on bio load. Water condition tests shouldbe done weekly to make sure levels are not spiking.
- Water Changes: Weekly – Do a 30 – 50% water change weekly.
Aquarium Setup
The Black Ghost Knife Fish will spend most of its time near the bottom. But a full sized Black Ghost Knifefish is a big animal which requires a big home. You will need to eventually provide a tank containing 100 gallons or more if you plan on keeping one of these beauties into adulthood. A high quality filter is a must. A UV sterilizer is a smart thing to incorporate into your tank as well, as these fish are very sensitive to medications. The UV sterilizer will kill many diseases.
Provide them with a dimly lit tank and you will have a happy Black Ghost. A fine gravel substrate and many hiding places with plants, smooth rocks or aquarium safe wood is a necessity. Some aquarists will use a clear tube for the fish to hide in. This makes it feel secure, but also the aquarist can see it. They are nocturnal and will spend most of the daylight hours hiding in a safe and secure location. They do apprecaite a moderate to strong water flow as well. Once acclimated to their new home, they should come out of hiding at feeding time. Some have even been taught to feed from their keeper’s hand.
- Suitable for Nano Tank: No
- Substrate Type: Sand/Gravel Mix – Needs a fine gravel substrate.
- Lighting Needs: Low – subdued lighting
- Range ph: 6.0-8.0
- Hardness Range: 5 – 19 dGH
- Brackish: No
- Water Movement: Moderate – This is a species that will apprecaite a moderate to strong water flow.
- Water Region: Bottom – This species of knifefish spends most of its time near the bottom.
Social Behaviors
This is a peaceful fish and will not disturb its tank mates. However Black Ghosts can become aggressive with members of their own species and members of other, similar species. Other than that, they are usually quite timid. They do have a large mouth so small fish or invertebrates kept in the same tank may eventually become a meal for a hungry Black Ghost.
- Venomous: No
- Same species – conspecifics: Yes – Adults may quarrel if they don’t have enough space and hiding places to accomodate each fish.
- Peaceful fish (): Monitor – While it is not necessarily aggressive, it will eat anything small enough to be considered a meal.
- Semi-Aggressive (): Monitor
- Aggressive (): Threat
- Large Semi-Aggressive (): Monitor
- Large Aggressive, Predatory (): Threat
- Safe – They are peaceful with larger tank mates that are big enough to not be considered food.
- Shrimps, Crabs, Snails: Threat – is aggressive – In the wild, this fish hunts at night for worms, crustaceans, insects and snails.
- Plants: Safe
Sex: Sexual differences
Sexual differences are unknown.
Breeding / Reproduction
This species is being bred commercially in Indonesia but the method used is unknown. There are hobbyists that claim to have successfully bred the Black Ghost Knifefish in an aquarium but they seem reluctant to share the details. There is some information on this subject, scattered reports, but there is nothing yet documented from reputable sources so it will not be reproduced here. One thing for certain is that if you want to give it a try, you’ll need a big aquarium, probably containing 100 gallons or more.
- Ease of Breeding: Difficult
Fish Diseases
These fish are hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won’t have to deal with health problems or disease. The Black Ghost does not have scales which make it more prone to disease. Black Ghost are normally the first fish in a tank to show signs of ick and will twitch and rub around the tank. They respond well to most medication and normally heal quickly. NEVER use copper in a Black Ghost Knife Fish tank.
Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.
When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish is more likely to acquire disease.
As with most fish the African Knife are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments .
Availability
The Black Ghost Knifefish are available all year long, especially now that they are being bred in captivity. Odds are that if you see an individual of 5 inches or more offered of sale, it was collected in the wild. Specimens smaller than 5 inches were most likely produced in and imported from Indonesia. Large specimens may command a high price, mainly due to the higher costs of shipping them. Smaller specimens are quite affordable.
- Animal-World References: Freshwater Fish and Plants
- Dr. Rüdiger Riehl and Hans A. Baensch, Aquarium Atlas Vol. 1 , Publisher Hans A. Baensch, 1991
- Glen S. Axelrod, Brian M. Scott, Neal Pronek, Encyclopedia Of Exotic Tropical Fishes For Freshwater Aquariums , TFH Publications, 2005
- Joseph S. Nelson, Fishes of the World , Wiley, 2006.
- Dr. Herbert R. Axelrod, Aquarium Fishes of the World , TFH Publications, 1998
- Dr. Herbert R. Axelrod, Dr. Warren E Burgess, Dr. Cliff W. Emmens, Neal Pronek, Jerry G. Walls, Ray Hunziker, Dr. Axelrod’s Mini-Atlas of Aquarium Fishes , Mini- Edition, T.F.H. Publications, Inc., 1987
- Apteronotus albifrons (Linnaeus, 1766) Black ghost , Fishbase.org
Apteronotus albifrons (Image Credit: Vassil, Wikimedia Commons CC0 1.0 Universal )
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Best 23 White Ghost Knife Fish
Below is the best information and knowledge about white ghost knife fish compiled and compiled by the onthihsg.com team, along with other related topics such as: ghost knife fish tank mates, can ghost knife fish live with cichlids, ghost knife fish size, ghost fish, black ghost, buy fish online, the black ghost knife fish, aquarium fish online

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1. Fun Ghost Knifefish Facts For Kids – Kidadl
Author: kidadl.com
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Summary: Articles about Fun Ghost Knifefish Facts For Kids – Kidadl The Ghost knife fish belongs to the family Apteronotidae. They are of the Actinopterygii class and Ictiobus genus. The freshwater fish primarily prey on insect …
Match the search results: There are around 89 species in the ghost knife fish family and there exist differences in the size and weight of every fish. Several fishes such as the Melanosternarchus fish and Adontosternarchus fish are around 6-10 in (15-25 cm) in length while species such as the black ghost knifefish (Apteronot…
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2. GHOST KNIFE FISH WHITE 6CM – Warragul Pet Emporium
Author: warragulpetemporium.com.au
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Summary: Articles about GHOST KNIFE FISH WHITE 6CM – Warragul Pet Emporium White Ghost Knifefish 8cm(Apteronotus albifrons)Temperature is ideal between 24-28C & pH 6 ? 8. I am feeding on Repashy Grub Pie Gel Food that I also sell …
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3. WHITE GHOST KNIFE – 5 for $50
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4. The Ultimate Black Ghost Knifefish Care Guide: Size, Tank …
Author: www.everythingfishkeeping.com
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Summary: Articles about The Ultimate Black Ghost Knifefish Care Guide: Size, Tank … Black Ghost Knifefish Overview · Experience Required: Moderate. · Nicknames: Black Knife. · Color Forms: Black and white. · Size: 18-20 inches.
Match the search results: You should also avoid other species of Knifefish (e.g. Brown Ghost or Glass Knifefish) as they too emit conflicting electrical signals which will cause distress for the both of them.
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5. Knife Fish – Sims Tropical Fish
Author: simstropicalfish.co.uk
Evaluate 3 ⭐ (13381 Ratings)
Summary: Articles about Knife Fish – Sims Tropical Fish Knife Fish · Black Ghost Knife Fish Apteronotus Albifrons 10cm · Clown Knife Fish Notopterus Chitala 10cm · Golden Clown Knife Fish Notopterus Chitala 10cm · Albino …
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6. Black Ghost Knife Fish – Care, Breeding, Diet, and Tankmates
Author: www.fishparenting.com
Evaluate 4 ⭐ (32864 Ratings)
Top rated: 4 ⭐
Lowest rating: 2 ⭐
Summary: Articles about Black Ghost Knife Fish – Care, Breeding, Diet, and Tankmates Besides having a blade-like structure, this creature has its nose containing a white strip followed by two white rings on its tail. The long, …
Match the search results: Other than ghost knife fish, you have options such as catfish, rope fish, angelfish, mono sebae, and corydoras as tankmates. While keeping small fishes, you need to ensure the big ghost knife is on the smaller side in comparison to prevent it from preying on smaller ones.
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7. Black Ghost Knife Fish Ultimate Care Guide 301
Author: fishcamprehab.com
Evaluate 4 ⭐ (24915 Ratings)
Summary: Articles about Black Ghost Knife Fish Ultimate Care Guide 301 Black Ghost Knifefish Facts & Overview ; Care Level: Intermediate ; Temperament: Semi-aggressive ; Color Form: White and Black ; Lifespan: 10 to 15 …
Match the search results: Black Ghost Knifefish is able to both emit as well as receive electric signals. An organ located in the tail produces electricity. These cells are found on the skin of fish and serve two purposes: communication and electrolocation.
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8. Fish of the week – Black ghost knifefish – NT Labs
Author: www.ntlabs.co.uk
Evaluate 3 ⭐ (12454 Ratings)
Summary: Articles about Fish of the week – Black ghost knifefish – NT Labs … week’s Fish of the Week: the black ghost knifefish (Apteronotus albifrons). This unusual species is completely black with only two white …
Match the search results: If you’re looking for an easy-to-care-for oddball for an aquarium the size of a small house (alright, not quite, but very large!), you might like to consider this week’s Fish of the Week: the black ghost knifefish (Apteronotus albifrons). This unusual species is completely black with onl…
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9. Black Ghost Knifefish – Care, Diet & Breeding – Aquarium Info
Author: blog.aquariuminfo.org
Evaluate 3 ⭐ (2475 Ratings)
Summary: Articles about Black Ghost Knifefish – Care, Diet & Breeding – Aquarium Info The Black Ghost Knife Fish is a tropical freshwater aquarium fish … Aside from the two white strings on its tail and a white stripe on its …
Match the search results: Ghost Knife Fish can be very shy when introduced to the aquarium. As mentioned before, they are nocturnal creatures and generally are most active at night. It will take a number of days to weeks for the Ghost Knife to recognize you as it’s food supply, at which point the Ghost Knife should become mo…
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10. White spot on black ghost knifefish | Oddball Fish Forum
Author: www.fishlore.com
Evaluate 3 ⭐ (4133 Ratings)
Summary: Articles about White spot on black ghost knifefish | Oddball Fish Forum Today u noticed a white spot on my black ghost knifefish, what could be the problem?
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11. Best 14 White Dragon Knife Fish – Học Điện Tử Cơ Bản
Author: hocdientucoban.com
Evaluate 3 ⭐ (11921 Ratings)
Summary: Articles about Best 14 White Dragon Knife Fish – Học Điện Tử Cơ Bản Match the search results: The Black Ghost Knifefish is one of the most popular Knifefish. It was …
Match the search results: Below is the best information and knowledge about white dragon knife fish compiled and compiled by the hocdientucoban.com team, along with other related topics such as: white ghost knife fish, white ghost knife fish for sale, pelican knife fish, aquarium fish online, white ghost fish, senegal fish, …
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12. White Spot Treament For Black Ghost Knife Fish
Author: www.fishforums.net
Evaluate 4 ⭐ (35313 Ratings)
Summary: Articles about White Spot Treament For Black Ghost Knife Fish Basicly we have had an esablished rena 340l tank running with a fluvl 404 which has been going well for 3 years,qwith hardly any fish deaths …
Match the search results: FishForums.net is one of the internet’s oldest and premier Tropical Fish and Aquarium forums! We are a family friendly community with an incredible resource of information for fish owners and enthusiast alike.
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13. White Ghost Knife Fish – A1 Aquarium World
Author: www.a1aquariumworld.com.au
Evaluate 4 ⭐ (34506 Ratings)
Summary: Articles about White Ghost Knife Fish – A1 Aquarium World White Ghost Knife Fish. Regular price: $34.95. Sale price: $34.95; Regular price. Sale Sold out. Unit price: /per. Tax included. Size. small 6cm, medium 8cm.
Match the search results: [email protected]
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14. Black ghost knifefish articles – Encyclopedia of Life
Author: eol.org
Evaluate 4 ⭐ (32634 Ratings)
Summary: Articles about Black ghost knifefish articles – Encyclopedia of Life The black ghost knifefish (Apteronotus albifrons) is a tropical fish belonging … The fish is all black except for two white rings on its tail, and a white …
Match the search results: The kind of EOD produced can be used to distinguish between two types of weakly electric fish: the pulse-type and the wave-type. The black ghost knifefish are considered to be the latter type, because they can continuously generate EODs in small intervals. Wave-type EODs have a narrow power spectra,…
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15. Black Ghost Knife Fish Care Guide
Author: theaquariumguide.com
Evaluate 4 ⭐ (23153 Ratings)
Summary: Articles about Black Ghost Knife Fish Care Guide As you can imagine, the black ghost knifefish is a solid black color with only a few white decorations. The white spots are seen on their tails and their …
Match the search results: Catfish and tetras are good with the black ghost knife fish, but make sure the aquarium mates you add are not small enough to be mistaken for food. Another instance where they can be aggressive is if the tank is too small, so make sure you have a large tank for all the species you plan to keep. A go…
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16. Knifefish Care Guide – Aqueon
Author: www.aqueon.com
Evaluate 3 ⭐ (1293 Ratings)
Summary: Articles about Knifefish Care Guide – Aqueon Knifefish are some of the most interesting freshwater aquarium fish available. … They include ghost knives, banded knives and glass knives.
Match the search results: Since some knifefish grow to be relatively large and most live long lives, appropriate plans should be made when purchasing them. Ghost knives, featherfin knives and African knives attain lengths of 8″ to 12″, requiring an aquarium of at least 55 gallons when full grown. Banded knives require at lea…
- [browser-shot url=”https://www.aqueon.com/resources/care-guides/knifefish” width=”600″]
17. Ghost Knifefish – White (Rare!) SS-5 – Aquatic Solutions
Author: aquaticsolutions.com.au
Evaluate 4 ⭐ (37319 Ratings)
Summary: Articles about Ghost Knifefish – White (Rare!) SS-5 – Aquatic Solutions Ghost Knifefish – White (Rare!) … wholesale business specialising in supplying aquarium stores, pet stores and zoos with quality ornamental aquarium fish.
Match the search results: Aquatic Solutions is a family run aquarium wholesale business specialising in supplying aquarium stores, pet stores and zoos with quality ornamental aquarium fish. We ship Australia Wide!
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18. Black ghost knifefish (Apteronotus albifrons) – Meethepet.com
Author: meethepet.com
Evaluate 3 ⭐ (4995 Ratings)
Summary: Articles about Black ghost knifefish (Apteronotus albifrons) – Meethepet.com The body is black with a white line on its back and two yellow-white transverse stripes on its tail stalk. The black ghost knifefish is one of …
Match the search results: The black ghost knifefish is compatible with any non-aggressive species except small fishes like neon tetra or guppy, which it will treat as food.
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19. Black Ghost Knife Fish (Apteronotus albifrons)
Author: badmanstropicalfish.com
Evaluate 4 ⭐ (37108 Ratings)
Summary: Articles about Black Ghost Knife Fish (Apteronotus albifrons) Unsurprisingly, the Black Ghost Knife fish features a thin, long, and knife-shaped body that is entirely black, except for a white stripe on its …
Match the search results: The Black Ghost Knife fish is a territorial species. Other than that, these fish are timid, so don’t put in aggressive fish that might beat up your black tropical fish. Also, don’t add in nano fish; they will become a meal for your Black Ghost Knife fish as they grow bigger.
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20. Black Ghost Knifefish – Profile | Traits | Facts | Care – SeaFish
Author: www.seafishpool.com
Evaluate 3 ⭐ (14017 Ratings)
Summary: Articles about Black Ghost Knifefish – Profile | Traits | Facts | Care – SeaFish Black Ghost Knifefish, scientific name Apteronotus albifrons, … fish that’s an all-over inky black shade apart from a white patch on the …
Match the search results: Keeping a black knife is beneficial for knowledgeable aquarists as a result of the fish is kind of delicate to circumstances.They are normally stored singly or in a standard aquarium with different appropriate species. For an adult black ghost knifefish, an aquarium of no less than 200 liters is req…
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21. Black Ghost Knifefish: Info with Care Details and Pictures
Author: www.thepetstep.com
Evaluate 3 ⭐ (8618 Ratings)
Summary: Articles about Black Ghost Knifefish: Info with Care Details and Pictures Know about the black ghost knifefish and their behavior. … Colors, Full black body apart from two white rings on the tail, and patches of …
Match the search results: The black ghost fish has ghost associated to its name as many South American natives believed that the souls of the deceased inhabited in them.
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22. Buy Black Ghost Knifefish, Fish & Livestock Online in Singapore
Author: fishyhub.com
Evaluate 4 ⭐ (21676 Ratings)
Summary: Articles about Buy Black Ghost Knifefish, Fish & Livestock Online in Singapore Largest variety of Monster Fishes | Livestock | Black Ghost Knifefish is a Large size,Medium care level,Semi Aggressive temperament,Low PH fish knifefish …
Match the search results: Minimum Tank Size: 75 – 200 gallonsCare Level: ModerateTemperament: Semi AggressiveAquarium Hardiness: Hardy as adultsWater Conditions: 73 – 82° F, 5 – 19 dGH, pH 6.0-8.0Max. Size: 20″Color: BlackTank Compatability: Mid level swimmer, aggressive to smaller fishDiet: Omnivorous and will readily consu…
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23. Black Ghost Knifefish – Apteronotus albifrons – Animal-World
Author: animal-world.com
Evaluate 3 ⭐ (8109 Ratings)
Summary: Articles about Black Ghost Knifefish – Apteronotus albifrons – Animal-World It has a broad whitish band just in front of the caudal fin (tail fin) and another narrower white band just before the tip of the tail. Size of fish – inches: …
Match the search results: The Black Ghost Knifefish Apteronotus albifrons was described by Linnaeus in 1766. They are found in South America throughout much of the Amazon River and its tributaries. The species is not listed on the IUCN Red List. Other common names they are known by are Black Ghost and Black Ghost Knife Fish.
- [browser-shot url=”https://animal-world.com/encyclo/fresh/Knifefish/BlackGhostKnifefish.php” width=”600″]
Video tutorials about white ghost knife fish
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Updated: April 27, 2022 112.0K views 4 shares 4 4 The black ghost knife fish is one of the most interesting and unique freshwater species that we've ever seen. When you see one in person you won't forget it! Because of their appearance, these fish have gotten a fair amount of attention from the aquarist community.
Habitat of the Knifefish. Though habitat choice depends on the species at hand, many in this group have similar preferences. They often utilize fast-moving waters, like creeks and streams. Many species also prefer deeper waters with little light penetration. Those that live in deep rivers live below 16 ft. or more.
Freshwater Fish. Oddballs & Predators. Knifefish. ... Double Fin Black Ghost Knifefish (Apteronotus albifrons) $ 34.99. Details. Notify Me. Duck Head Knifefish (Parapteronotus hasemani) $ 69.99. Details. Notify Me. Congo Black Knife (Papyrocranus congoensis) $ 44.99 - $ 59.99. Details. Notify Me. Goldline Knifefish (Sternopygus macrurus) $ 44 ...
D. S. Jordan, 1923. The ghost knifefishes are a family, Apteronotidae, of ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. [1] They inhabit a wide range of freshwater habitats, but more than half the species in the family are found deep in rivers (typically deeper than 5 m or 16 ft) where there is ...
Knifefish are scaleless and extremely sensitive to poor water conditions. Water quality should be pristine, with undetectable ammonia and nitrites, and nitrates below 20 ppm. pH should be between 7.0 and 8.0, with alkalinity between 5° and 10° (90 ppm to 180 ppm). Temperature should be maintained between 75° and 80° F.
The clown featherback ( Chitala ornata ), also known as the clown knifefish and spotted knifefish, is a nocturnal species of tropical fish with a long, knife-like body. This knifefish is native to freshwater habitats in Cambodia, Laos, Thailand, and Vietnam, [2] but it has also been introduced to regions outside its native range. [1]
White Ghost Knifefish are best kept with tank mates that are not too boisterous or aggressive. Discus, Geophagus, Severum, Angelfish, peaceful Catfish, peaceful Cichlids and larger (6 inches or more) community species make good tank mates.
Here's my care guide / species spotlight on how to look after a ghost knife fish. My Ghost knife fish is one of the most interesting fish in my fish tank and...
Updated on Aug 3, 2023 by Peter Herzog Not every freshwater aquarium needs a burst of vibrant color. Sometimes you want something unusual as the centerpiece of your tank. And if you want a genuine conversation piece? You couldn't ask for better than the black ghost knife ( Apteronotus albifrons ).
The fish is all black except for two white rings on its tail, and a white blaze on its nose, which can occasionally extend into a stripe down its back. It moves mainly by undulating a long fin on its underside. It will grow to a length of 18"-20". Only a fish for those with large aquariums, minimum 100 gallons. Black ghost knifefish are nocturnal.
Black Ghost Knifefish are very popular - they are a mesmerizing and elegant fish that will steal your heart in no time. From ghost stories of tribes in South America to electrogenesis, this fish will Black Ghost Knifefish Care Guide: All You Need To Know | Fishkeeping World Toggle Menu Freshwater Fish Betta Fish Cichlids Otocinclus Angelfish Plecos
Be the first to review this product. White Ghost Knife Fish Apteronotus leptorhynchus. $34.80. Availability: Out of stock. SKU. TZ167060. Buy 4 for $31.32 each and save 10%. Buy 8 for $27.84 each and save 20%. Notify me when this product is in stock.
Overview. The Black Ghost Knifefish is a member of the Apteronotidae family and the speckled knifefish group. It is considered a true bony fish. When properly cared for, the Black Ghost Knifefish can reach well over one foot in length. It possesses a weak electrical organ at the caudal peduncles which is used to locate food.
They generally do fine with pH of 6.8-7.8, temperature between 75-82°F (24-28°C), and at least 5° (90 ppm) GH. Create a heavily decorated setup with low lighting and lots of nooks and crannies — such as clear PVC pipes, rock caves, pleco caves, large driftwood, and aquarium plants.
Introduction The Black Ghost Knifefish is a fascinating freshwater species from South American rivers with abundant vegetation. It utilizes its electric organ discharge (EOD) for communication and orientation in the dark, making it one of the most remarkable electric fish on earth.
The black ghost knife fish (Apteronotus albifrons) or any other species of the ghost knife breed only after attaining maturity. The exact process of breeding in freshwater or rivers is not known. But the black ghost knifefish are bred in fish tanks, large aquariums, and ponds. Several water parameters such as the optimum breeding temperature ...
The ghost knife fish apteronotus albifrons is quite sensitive to changes in water parameters, which is what makes them less suitable for beginners. One of the most important factors to ensuring the health and longevity of the black ghost knife is the water conditions. ... The disease manifests as white spots and patches on the fish's body ...
The Black Ghost Knife Fish ( Apteronotus albifrons) is an interesting aquarium fish that originates in South America. They have a long body that is shaped like a knife. They will grow to a significant size, but they are agile fish that are able to maneuver around objects in the tank. They will also live a long time if they are well cared for.
For this reason, check what you're buying and ensure you're getting a healthy ghost black knife fish. Look for the white spots on the tail of the fish. Lifespan. A well taken care of black knife ghost fish can live for about 10 years or sometimes even more when kept in optimal conditions. Some even claim that they can reach up to 15 years.
Availability 12. References The Black Ghost Knifefish is the most well known species of knife fish in the aquarium industry! The Black Ghost Knifefish Apteronotus albifrons is the most popular knife fish. One reason for this is that they have been imported for decades. Other reasons include being unusual, interesting and amazingly beautiful.
Summary: Articles about White Ghost Knife Fish - A1 Aquarium World White Ghost Knife Fish. Regular price: $34.95. Sale price: $34.95; Regular price. Sale Sold out. Unit price: /per. Tax included. Size. small 6cm, medium 8cm. Match the search results: [email protected].
Black Knife Ghost Fish with Ich (white spots) Search. Advanced search. Sponsors. Recent Topics. Co2 standard light algae by jacquie [April 26, 2023, 10:54:24 am] Grey hair by Sid1960 [March 18, 2023, 06:18:07 pm] Suggestions for a one spe... by Malfie [March 04, 2023, 07:29:31 pm]