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Black ghost knife with cichlids?

  • Thread starter pengu13
  • Start date Apr 30, 2010
  • Advanced Aquaria Discussion Forum
  • Ancient Fish
  • Knifefish and Lungfish

Feeder Fish

i noticed a 6" black ghost knife for sale wondering if it would work out in a large tank (300G) with cichlids like a texas , green terror, dempsey, red devil  

a very, very iffy maybe, and only if there are a lot of hiding spaces. Most likely not as the cichlids you have in there are quite aggressive  



I wouldn't do it... Those cichlids are way aggressive...maybe if the black ghost is bigger...but i wouldnt risk it  




Those are some pretty tough Cichlids. It's possible that it will live, but it won't be too happy in there.  



I had my 7" BGK in with a 13" Oscar, and two 6" Jack Dempseys for awhile, no issues.  

I wouldnt do that....the poor knife would just be getting beat up all the time. Even if he has hiding spaces, what happens when he comes out to grab something to eat? Those cichlids are probably going to tear him up.  


Jack dempsey.

It all depends on the ages and sizes of all parties, when introduced to one another. It's very risky, but if you introduce them to one another at a younger age, your chances for success are greater. Also, you do not want to introduce a NEW BGK to a well-established tankful of cichlids. They've probably established their territories and would just pick on your BGK to the point of death. Keep in mind that BGK's have a unique swimming pattern and they often bump into other fish and invade their personal spaces, because they have poor eyesight. An established cichlid has zero tolerance for that type of treatment from another fish.  

Thanks for the info all my cichlids are small right now 4-5" the guy said the black ghost knife is 6". it would have its own tank till my big tank was ready  

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American Cichlids with black ghost knife fish, instant disaster ????

  • Jul 12, 2016

HI I'm new to the forum although not new to keeping fish. I have recently started a slightly more boisterous tank than I have always kept in the past. we have always been fish people having always had tanks since I was a child and have now got my 5 year old boy into keeping his own tank ( which he probably cleans more than I clean mine lol ). My Question is, I have 2 x 2.5" Firemouths and 3 x 4.5" Geophaus cichlid 's and iv kind of fallen in love with black ghost knife fish and would love one as my feature fish but obviously I don't want it to be bullied by the cichlids and its well being comes first over my desire for it. I currently have a 400+ litre 4 foot tank with lots of rocky hiding places as well as driftwood , artificial plants with lots of open space still which I'm hoping would be big enough to keep it in for a while until I invest in a six footer next year. Sorry if this has been asked a million times before but I'm new to forums full stop when it comes to keeping fish as iv never had anything worth asking. Cheers rich  

Welcome to fishlore! Definitely envious of your future 6 footer. I think it's great you are doing the research needed. The ghost knife will likely need to upgrade at sometime (though I've seen people keep them in 4 foot tanks successfully) which the 6 footer will be perfect. What kind of geophagus do you have? In general firemouths and geophagus are pretty peaceful for cichlids so there is a reasonable chance it will be fine. But it will largely be up to the personality of your cichlids. I'd say it's worth a shot but you'll want a back up plan just in case.  

  • Thread Starter

can black ghost knife live with cichlids

Yeah...I mean I definitely think it's worth a shot. You'll just have to monitor and make sure the knife is getting food  

BGK's are one of my favorite fish. I just want to caution you on your say you want the BGK to be your feature fish....just keep in mind that MOST of them will only come out in the dark. They are nocturnal fish and unfortunately really are not "featured" much for the owner. But again, personalities differ. Some BGKs may be out during the day more, but it isn't common. My experience was that my BGK was very social and swam around the tank quite a bit when he was little. He even ate out of my fingers. As he got older and bigger, he became a bit more shy and spends most of his time in his hollow log ornament. He is about a foot long now. I love him so much!! I don't now about keeping them with American cichlids . Mine has spent his whole life in a peaceful community. His only American cichlid tank mates are angels . It will be a gamble for you, but as tyguy7760's worth a shot, but make sure you have a back up plan.  

The nocturnal aspect is one thing I hadn't given a massive amount of thought to if I'm honest and as you say if they spend most of the time hiding then a feature it will not be, especially as the fish already in the tank are mega shy at times so it looks empty as it is. There is just something about them that has instantly fascinated me and I really would like to learn more by homing one. The backup plan is a great idea but its something I am struggling to come up with as there is nowhere I could re-home if things didn't work out as I don't know anyone with a tank close to big enough. Believe me I have the BGK best interest at heart and won't even place one in my tank unless I'm completely happy. Iv heard some people saying that the Africans can make its like a misery but there just doesn't seem to be much info on relationships between Americans and BGK's. Also I use a very soft subdued lighting so I don't know if that would encourage more activity Thankyou all for your input and I'm looking forward to more  

Perhaps (as hard as this is) you should wait until you get your 6 foot tank before doing a BGK. This will give you another tank to rehome him to in case of emergencies and more time to research them.  

You are right, the African ones are much more aggressive than the American ones as far as I know. So good to stay away from those. Do you have any local fish stores (LFS) near you? Not the chains like petco or petsmart. More like the family owned ones? They will usually take fish from people if they outgrow their tanks, or if they have compatibility issues and the owner has to part with them for whatever reason....That could be a back up plan. The only fish none of my LFS would take was a common goldfish that my daughter won at a carnival. I had a heck of a time rehoming that thing!! Also, there are these clear tubes they make specifically for the BGK (or other long nocturnal fish) that will allow them to feel somewhat secure, but allow you to see observe them.... Maybe that would help? Edit, do you get to keep the 4 foot tank up when you set up the 6 foot tank? Do you get to have both? or will the 6 footer replace the 4 footer?  

Yeah the place my current fish came from is a small non-chain owned aquatics centre and they have a lot of their own private tanks of considerable size's so it may be worth speaking to them and seeing if they would have space if needed. Ha ha its a sore subject as the misses isn't as into the aquariums as me and the kids are, id like to run both so I can have all sorts of different breeds like I quite fancy some barracudas but they would have to be on their own. if I keep both and everyone gets on then all in my current tank would move up to the bigger and I would use the 4 footer for something else. tyguy7760 I get completely what your saying and the sensible side of me agrees but I'm finding it hard to switch off my fascination with them as they truly are an amazing fish so I will exhaust all options before I give up on an absolute tangent, how do u manage to get such good pics of your fish cos mine are 90% glass reflection and look naff  

Well the room that my tank is in right now is a relatively dark room and I use my cell phone to get as close to the glass as possible. If you put the phone right up on the glass it cuts down most of the glair  

Ahhh ok that makes sense, iv been using an Slr with a good zoom to try and take pics from across the room as they all hide when I go near the tank  

on an absolute tangent, how do u manage to get such good pics of your fish cos mine are 90% glass reflection and look naff Click to expand...
Ahhh ok that makes sense, iv been using an Slr with a good zoom to try and take pics from across the room as they all hide when I go near the tank Click to expand...

I personally would not keep diurnal fish with nocturnal fish as they will disrupt each other's sleep patterns (or rest patterns if you don't believe that fish sleep in the mammalian sense). I consider this to be stressful and not conducive to good health, disease resistance and subsequent long life.  

  • Jul 13, 2016

can black ghost knife live with cichlids

  • Jul 17, 2016

Ok so I went and spoke to my LFS about the possibility of using them as a potential back up plan and guess what they were just about to put on sale after its 2 week rest period, a couple of BKF. I'm sure you can guess where I'm going with this, I now have an amazing new addition to my tank. I also came away with a stunning gold severum to have as my feature fish as irl rarely see the BKF in the day, or so I thought, the thing Is active constantly only stopping to take a nap in his cave from time to time lol. I can't wait to watch this fish grow so I can study it further as its a remarkable thing from what iv seen so far. The severum seems to think its a geophagus and has joined their gang, roaming around the tank constantly scavenging for food with them.  

Congrats on the new fish! how big is the bgk right now? Mine was only 2-3 inches when I got him and he loved eating blood worms out of my fingers. It was fun you should try it  

  • Jul 18, 2016

cheers I'm well chuffed with them. Its between 5 and 6" so a reasonable size already. I really wanna try but its still a bit shy around me, although it has no problem with the other fish in the tank. When I first got the bkf it went straight and kicked the 3 geophagus out of their cave and made it its home, at first I felt bad for them but its actually worked out quite nicely. The geophagus now use a bigger cave and spend a lot more of their time out and exploring so has made for a much more active and social tank  

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can black ghost knife live with cichlids

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15 Best Black Ghost Knife Tank Mates – FishLab

Black Ghost Knife Tank Mates

It is natural to want a tank mate that can bring some color and liven up your Black Ghost Knife Fish! Let’s take a look at the 15 Best Black Ghost Knife Fish Tank Mates!

The 15 Best Black Ghost Knife Tank Mates are fish that are just as large as the Black Ghost Knife and can survive in the same water temperatures. These can include Rainbowfish, gouramis, and even several species of catfish. 

In this article, we will cover not just a list of our top picks for companions to the Black Ghost Knife Fish, but also what makes those companions suitable. We’ll even give you a rundown of what to watch out for in any tank mates in the categories below. Let’s get started!

Black Ghost Knife Tank Mates – What You Need to Know

When caring for a Black Ghost Knife Fish, the best way to keep yourself and your tank happy is to master the categories of knowledge below, especially when choosing tank mates.


The temperament of a Black Ghost Knife Fish is very peaceful. What you need is fish that can match that peacefulness instead of starting fights, being incredibly calm and relaxed. 

The size of the fish that are with the Black Ghost Knife Fish should be about the same as the Black Ghost Knife itself. Though it is peaceful, as mentioned above, it can also eat or intimidate smaller fish. Make sure to get tank mates that are not significantly smaller than 18 inches long.


 Food competition means that one fish who eats the same diet and in the same zone of the tank may bully another fish out of their share at mealtime. To avoid this, make sure fish are either able to fend for themselves at mealtime or have different diets. 

The Black Ghost Knife Fish eats a carnivorous diet of frozen and live foods like Brine Shrimp, feeder fish and earthworms.

Parameters ; Tank Setup

 The Black Ghost Knife Fish needs at least 100 gallons, being a very large fish. It should also have a temperature of water in the range of 75 to 82 F. If a fish finds this too warm or too cold, they won’t make a good tank mate for the Black Ghost Knife Fish!

15 Best Black Ghost Knife Fish Tank Mates

  • Silver Dollar Fish
  • Electric Blue Acara
  • Cory Catfish
  • Bristlenose Pleco
  • Dinosaur Bichir
  • African Rope Fish
  • Saddled Bichir
  • Eartheater Cichlid
  • Sailfin Molly
  • Green Swordtail
  • Balloon Molly
  • Glass Catfish
  • Pictus Catfish

Let’s look more closely at each of these catfish to see what makes them so great as tank mates to the Black Ghost Knife Fish!

  • Leopard Bush Tank Mates
  • Paradise Fish Tank Mates
  • Leopard Puffer Tank Mates
  • Bumblebee Cichlid Tank Mates

1. Silver Dollar Fish

shutterstock 199691657 9

  • Scientific Name: Metynnis argenteus
  • Adult Size: 6 inches
  • Compatible With: Black Ghost Knife Fish 
  • Care Level: Medium Difficulty
  • Origin: Guyana, Brazil

The silver dollar fish is sometimes considered difficult to take care of because it is so large. However, this fish is perfectly safe to be kept with your Black Ghost Knife Fish. 

The Silver Dollar Fish will add some shine to your aquarium. It has a round, silvery body, just like its name!

Pros of keeping with Black Ghost Knife Fish:

  • No food competition
  • No aggression

Cons of keeping with Black Ghost Knife Fish :

2. Electric Blue Acara

shutterstock 751187695

  • Scientific Name: Adinoacara pulcher
  • Adult Size: 7 inches
  • Care Level: Easy
  • Origin: Venezuela

Another gentle giant is the Electric Blue Acara. It is peaceful and will avoid starting trouble with your Knife Fish. 

However, it is worth noting that the Electric Blue Acara will spice up the visuals of the aquarium with its reflective light blue body, fringed beautifully on the dorsal fin with lightning-yellow. It is technically a cichlid, but the Electtric Blue Acara is no bully unlike other cichlids. 

3. Oscar Fish

shutterstock 1868527048 2

  • Scientific Name: Astronotus ocellatus
  • Adult Size: 14 inches
  • Care Level: Difficult
  • Origin: South America

The most difficult thing about keeping the Oscar Fish is that it can become so large. With an already-big fish like the Black Ghost Knife in the tank, you’ll need a very big tank indeed to accommodate both!

If you can, however, you’ll have two tank mates who are similar enough in size to avoid hurting one another. The piranha-like Oscar Fish will stay near the top of the tank, in general. 

  • Similar in Size
  • Large Tank required

4. Cory Catfish

shutterstock 1692333103

  • Scientific Name: Corydoras aeneus
  • Adult Size: 2 inches

Another South American fish, the Cory Catfish is small but peaceful and will stay on the bottom of the tank. There is also strength in numbers; this bottom-feeder likes to school with more of it’s own kind. 

Cory Catfish like the Bronze Cory are iridescent, looking bronze in color but showing a whole rainbow of dull hues under the right light.

  • Will clean up the bottom of the tank

5. Bristlenose Pleco

shutterstock 2243018505 9

  • Scientific Name: Ancistrus cirrhosus
  • Adult Size: 5 inches
  • Origin: Amazon

This is another bottom-dwelling fish that can not only survive in the same conditions as the Black Ghost Knife, but is quite peaceful. 

Named for its bristly whiskers, this fish will clean up the bottom of the tank! At the same time, it will look interesting. 

6. Dinosaur Bichir

shutterstock 2191183427

  • Scientific Name: Polypterus senegalus
  • Adult Size: 18 inches
  • Care Level: Medium difficulty
  • Origin: Africa

Another type of fish that is difficult mainly because it requires a very large tank, the Dinosaur Bichir works well as a tank mate for the Black Ghost Knife Fish. It is large enough to avoid getting eaten and mostly stays on the bottom of the tank.

As it lurks near the floor you’ll be able to see its long body structure. It even has a reptilian, snub-nosed, dinosaur-like face!

  • Different tank zone occupier

7. African Rope Fish

shutterstock 1186504066

  • Scientific Name: Erpetoichthys Calabaricus
  • Adult Size: 24 inches
  • Origin: Nigeria

This fish is famous for its cute face, despite its long, snake-like body. Rope fish are ancient, and are sometimes also called reedfish. 

True to its adorable facial expression, the African Rope Fish is pretty laid back and won’t bother your Black Knife Fish. 

8. Saddled Bichir

shutterstock 1669553131

  • Scientific Name: Polypterus endlicheri endlicheri
  • Adult Size: 30 inches

The saddled bichir has a sort of menacing look to its long body, flat head, and opaque eyes. However, it won’t bother your Black Ghost Knife Fish. 

An issue will only arise if there is not enough room in the tank. Saddled Bichirs need plenty of space, being one of the larger fish species. 

9. Eartheater Cichlid

shutterstock 1727338423

  • Scientific Name: Geophagus
  • Adult Size:  12 inches

This is another member of the cichlid family that is somewhat unpredictable in terms of temperament. Some smaller varieties are relatively peaceful, while larger ones live up to the cichlid name by terrorizing the rest of the tank. 

However, since this fish is usually around the same size as a Black Ghost Knife Fish, even if you do wind up with a grumpy fish, it may not do much harm. These fish are colorful without the protruding forehead of a usual cichlid. 

  • May not be aggressive
  • May be aggressive

10. Angelfish

shutterstock 1774574882 1

  • Scientific Name: Pterophyllum
  • Adult Size: 4 inches
  • Compatible With: Black Ghost Knife Fish 

This tropical fish is beautiful. It will certainly add the color that your Black Ghost Knife Fish lacks, and is famous for its bright range of rainbow hues.

This fish can be semi-aggressive to smaller species, but because it is smaller than the Black Ghost Knife Fish, it won’t cause trouble. 

  • May have aggressive habits

11. Sailfin Molly

shutterstock 1992640667 3

  • Scientific Name: Poecilia latipinna
  • Adult Size: 3 inches
  • Compatible With: Black Ghost Knife Fish
  • Origin: Louisiana

This fish is fun to watch just for looks alone! It is covered in pretty brown specks over its blue to silver body. It has a long, sail-like dorsal fin and protruding lips. 

This fish will not only survive in the same parameters as a Black Ghost Knife Fish, but it is fast and capable enough to avoid causing trouble with the bigger fish. 

12. Green Swordtail

shutterstock 223356973 1

  • Scientific Name: Xiphophorus helleri
  • Origin: Central America

The swordtail is named for its hilt-like tail fins. It is brightly colored, coming in all sorts of hues, with especially long and beautiful fins. 

Though this fish is smaller than the Black Ghost Knife, it is quick and peaceful. As long as there is room and shelter, it will not be preyed upon. 

13. Balloon Molly

shutterstock 2002797047 3

The Balloon Molly treats us to a unique appearance thanks to a spine deformity that slops it’s back, making it look like it has a potbelly!

This fish comes in many warm colors and is largely peaceful. It eats an omnivorous diet, but because of its smaller size it will not hog the Knife Fish’s food. 

14. Glass Catfish

shutterstock 1706097715

  • Scientific Name: Kryptopterus bicirrhis 
  • Origin: Asia

The glass catfish is named for one interesting fact that will blow your mind: it looks transparent! You’ll find a pair of whiskers and what looks like a fish skeleton floating in your tank. 

It will do no harm to your black ghost knife fish, either. 

15. Pictus Catfish

shutterstock 2169049259 1

  • Scientific Name: Pimelodus Pictus

Finally, many aquarium hobbyists love the ease with which they can care for the Pictus Catfish. It can survive in many different scenarios and cleans the tank up while doing it. Being a bottom-dweller, it poses no threat to the Black Ghost Knife Fish. 

These fish are bright silver with whiskers as long as their bodies, forked fins, and pleasant little black spots. 

  • Will clean up the tank

In Conclusion

The 15 Best Black Ghost Knife Fish Tank Mates are those that can not only survive in similar water conditions, but are not too small to be safe from getting eaten, nor too aggressive to disturb the peaceful fish.

Some examples of these include the Pictus Catfish and the Balloon Molly! With these fish, you’ll have no trouble with a large, peaceful aquarium community.

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black ghost knifefish with cichlid??

  • Thread starter anthonylam
  • Start date Sep 1, 2005
  • Get the NEW AquariaCentral iOS app --> // Android version will be out soon!
  • Freshwater Topics

hi i have a 55-60gal. i was thinking of having a black ghost knifefish in the tank. then i also thought of adding an oscar or a green terror(aequidens rivulatus)... which means... 1 black ghost + 1 large cichlid. after doing some research... it doesn't seem that i can have a large cichlid in the same tank as a black ghost. what do u think? pls give me some feedback. thank u.  


well, the species profile of bgk on other sites say that 60 gals would be enough for an adult... about 40cm... anyway.. if i had a tank with 3 silver dollars, 2 striped raphaels, and a sailfin pleco... and have space and the intention to add one more fish... would it be oscar or green terror or black ghost... which would have more personaltiy? all grow to about 12-16 inches.  

sumthin fishy

sumthin fishy

BGK like to sleep all day. They do have wonderful personalities, and you can train them to hand feed. But if you are looking for something more active, go with the cichlid. You will have to get your hands wet anytime you want to show off the knife. Since the BGK is practically blind, it will have problems defending itself against the more agressive, and optically advantaged beast. If you absolutely had to do it, make sure to have a good slender hiding place for the knife  


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