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African Knifefish

African Knife Fish, Brown Knifefish, Black Knifefish

Family: Notopteridae African KnifefishXenomystus nigriPhoto © Animal-World: Courtesy David Brough

  The African Knifefish is a most intriguing fish for many Aquarists, and is one of the most popular species of knife fish available!

   One of the easiest species of knifefish to care for, the African Knifefish is hardy and generally more outgoing than other species of knifefish. This knifefish makes a good candidate for a community aquarium containing medium to large sized fish.

   What the African Knifefish lacks in color, it more than makes up in hardiness and personality. Most species of knives are very shy and rarely seen during daylight hours. The Notopteridae family contains some of the more outgoing species but some of these, such as the Clown Knifefish, can grow to huge proportions. In the wild, the African Knifefish can grow as large as 12 inches, but a maximum size of around 8 inches is more realistic for a tank raised specimen. Since they are wild caught, they may seem shy at first, but given time they will come out of their shell.

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Habitat: Distribution / Background

   The African Knifefish was described by Günther in 1868. They are found in many of the coastal rivers of Africa including the Congo, Nile, Niger, Ogooue, and Chad River basins. Most of the specimens that make it into the aquarium hobby are exported from Nigeria.

• Scientific Name: Xenomystus nigri
• Social Grouping: Solitary - Can become belligerent to their own kind.
• IUCN Red List: NE - Not Evaluated or not listed - The species is not listed on the IUCN Red List.

Description

The uniform blackish gray brown body of the African Knifefish is flat and elongated with an arched back. It has a continuous fin along the underside formed by a joining of the caudal and anal fin. It is a graceful swimmer and this fin allows it to move both forwards and backwards. An interesting characteristic is its ability to emit a bell-like sound, produced by ejecting air from its swim bladder.

• Maximum Size: 12.0 inches (30.48 cm) - In the wild, the African Knifefish can grow as large as 12" (30 cm), but a maximum size of around 8" (20 cm) is more realistic for a tank raised specimen.

Fish Keeping Difficulty

• Aquarium Hardiness: Moderately hardy
• Aquarist Experience Level: Intermediate

Foods and Feeding

   The African Knifefish are carnivores. In the wild they begin to eat when the sun sets and continue throughout the night, feeding on worms, crustaceans, insects and snails. A tank of around 55 gallons is large enough to keep an adult in good condition for all of its life. They are one of the few species of knife fish that will eat dried foods such as flakes and sinking pellets. A varied diet is important so be sure to also feed some fresh or frozen foods such as brine shrimp or bloodworms. They will eat small fish but this is more of a warning that small tank mates may disappear, not a suggestion for feeding.

• 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

Aquarium Care

• Water Changes: Monthly

Aquarium Setup

• Minimum Tank Size: 55 gal (208 L)
• Suitable for Nano Tank: No
• Substrate Type: Any
• Lighting Needs: Low - subdued lighting - Prefers low lighting but can be comfortable in aquariums with moderate to high lighting if there are places to hide.
• Temperature: 72.0 - 82.0° F (22.2 - 27.8° C)
• Range ph: 6.0-8.0
• Hardness Range: 5 - 15 dGH
• Brackish: No
• Water Movement: Weak
• Water Region: Bottom - This species of knifefish will spend most of its time near the bottom, although they will occasionally swim to the surface to grab a gulp of air.

Social Behaviors

  They are peaceful towards other species but adults will sometimes turn aggressive towards others of their own kind. They do have a relatively large mouth so smaller tank mates may disappear. Some of the Mormyridae fishes, such as the Elephantnose and the Baby Whale make good tank mates as do Synodontis catfish.

• Venomous: No
• Temperament: Semi-aggressive
• Compatible with:
  • Same species - conspecifics: No
  • Peaceful fish (): Monitor - Since the african knifefish is a carnivore, it will eat small fish. They are peaceful with larger tank mates that are big enough to not be considered food.
  • Semi-Aggressive: (): Threat
  • 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 fish has been bred in an aquarium.

• Ease of Propagation: Difficult

Availability

  The African Knifefish is commonly available.

References

Animal-World References
Freshwater Fish and Plants -  Tropical Fish ~ Freshwater Fish ~ Aquatic Plants

Author: Ken Childs

• African Knife : $8.59
• African Knife : $9.99

African Brown Knife Offered By: PetsMart Price: $8.59

African Knifefish 4 6 Length Offered By: PetCo Price: $9.99

Lastest Comments on African Knife Fish View all 16 comments on African Knife Fish Add Your Comment

Ito - 2011-11-29 I'm thinking about getting an African brown knife. What is the smallest tank mate that won't get get eaten? Are cherry barbs, mollies and cory cats too small? Click For Replies (2) Charlie Roche - 2011-11-30 I think they would be too small. The Knife fish can go to 12 inches and if it fit in their mouth - they will eat it. Anonymous - 2012-01-14 Cory cats might be ok because they have spines so they wont eat them Reply

Fish Dude - 2010-05-28 I saw one of these in petsmart, and the care sheet said 20+ gallons. Is this right? Or is that way too small? Because I have a 20 gallon and think these fish are really cool. Click For Replies (7) Editor's Note - 2010-05-29 Since these guys only get to about 8-12 inches in the aquarium, 20 gallons would be fine if you go by the 1 inch per gallon rule. Since all 8-12 inches are in one fish though, you should be very conservative with it. Like if the fish actually gets to 12 inches 20 gallons would be an absolute minimum. brandon - 2010-05-31 Most likely the fish won't get to a full foot probably around 9 inches I'd say this is fine but if you want other fish you may consider getting a larger tank. ryan - 2010-07-20 I have an African knife fish and he was in my 75 gal tank, but he is very territorial so I moved him into a 10 gallon and he is doing well. So the only thing I can say is that he won't get that big in a 20 gallon tank. justin - 2011-01-15 Tha's gonna be too small. These guys can grow up to a foot. david - 2011-06-15 Tank volume determines how many fish you can keep. An initial stocking guide is one inch per 1.2 gal (4.5 l) of fish length, excluding the tail. But this applies only to "average-sized" fish (up to 1.5 in/4 cm) in normally proportioned tanks. Weight-to-length ratio rises significantly after that, and larger fish produce more weight-so a 12 in (30 cm) Oscar needs more room than 12 Neon Tetras, each measuring one inch (2.5 cm). Remember that the fish in shops will probably be juveniles. Make due allowance for growth. vince - 2011-06-30 I have a knifefish in a 10 gallon aquarium for about a month now and it is doing fine. I also have tetras, mollies, blacktail shark and 3 albino cats and so far he has not disturbed them one bit. Make sure you have somewhere for him to hide and don't expect him to come out much. Pretty much the only time I see him is at feeding time. Good luck jake - 2012-01-13 20 gallons is too small for that fish. You should never listen to the 1 gallon per inch of fish. this fish will need a 55 gallon at the least when it is little you can have it in the 20 gallon but they get big and you will need a big tank as they get older Reply

john - 2011-12-07 I would like one of these to live with my senegal bichir who is TEMPORARALY in a 5 gallon tank and I plan on moving him to a 20 gallon tank and as a friend for him. would this be idea? Fish that i am thinking for the 20 gallon are a pair of firemouths,this fish,senegal bichir,feeder guppies,and a fish called the bornean leaffish.these are fish that i want to put in, but not all. Click For Replies (2) Nick - 2011-12-29 I would not house one in that small of a tank, neither would I house firemouths or bichirs in that size tank. They all get too big for a 20g, I would instead go for a 75g jake - 2012-01-13 Most of these fish need 55 gallon and up 20 gallon maybe as a temperary tank but the firemouths will get 7 to 12 inches and the knife fish with range from 6 to 9 inches so you can keep them in a 20 gallon untill they are about 3 or 4 inches then move to a 55 and up if you have the bichir for a while it will get huge Reply

osama - 2008-11-01 Can I put the african knife fish with cichlids family fish? Click For Replies (10) Katie - 2010-03-05 I probably wouldn't. A lot of the cichlids will pick on the knife. Robert - 2010-03-21 I would say probably not, my sister had a oscar in with her knifefish and the oscar tried to attack it. But im not quite sure other cichlid species would do this but i probably wouldn`t try it. nate - 2010-04-21 Yes I keep mine with my oscar fish and they get along great! Shawn K - 2010-06-17 My vote is maybe...Depends on the aggression level of your type of Cichlid, I had a Salvini and it straight up attacked and chased my knife for 2 days before I ditched the Salvini...I later found this is a more aggressive species of cichlid. If you have Kribensis or yellow labs (2 of the more agreed non-psycho cichlids) it'll probably be OK. demetris - 2010-08-25 It's recommended not to but I have one with 2 jack dempseys, 1 albino tiger, 1 parrot blood, a bichir loach, and a striped peacock eel in a 75 gal tank and the only ones that bother each other are the dempseys and the parrot over dominance of the tank but they don't bother the knife fish. zack - 2010-10-05 Yes I got several cichlids with my clown knife and they all get along pretty good. Andrew - 2010-12-30 YES! I have a african knifefish with 3 african cichlids and they get along just fine. The cichlids will occasionally chase it around but most of the time they leave each other alone. And the knife even chased the cichlids around for a while too! Great and cool fish. Kevin - 2011-11-21 I have a (fairly large)African knife fish in with about 15 peacock ciclhids..they seem to get along Bill Lacks - 2011-11-21 I got 2 knife fish 1 jack dempsy and red devil in a 55 gallon tank they get along good so far. jake - 2012-01-13 Cichlids are tricky fish. You never know what will happen to your fish unless its a betta or guppy or somthing like that. Also it depends on what cichlids African or American. African might tare the thing apart or they might never bother the fish at all. American cichlids get big. They would have to be around the same size as the knife fish so the oscar, jack dempsey and other American cichlids will not beat it up or eat it Reply

Fish Dude - 2010-10-29 Hello I've got a question, I'm getting a 55 gallon tank. And I already have fish in a 30 gallon that I want to move to the bigger one. But I need to know what won't be eaten by the knife fish. I have already know for sure that my neon tetras and zebra danios would be instant food, but what about glass (ghost) catfish, a bristlenose pleco and a clown loach? And one more thing, I'm also interested in Spotted Climbing Perch (or African Bush Fish, whatever you want to call it). Can it live with the knife fish and the other fish described above? Thanks! Click For Replies (4) justin - 2011-01-15 It will eat anything small enough to fit in its mouth... I also have clown loaches with my brown knife and they look great together! wendi - 2011-03-28 We have this fish with Neon Tetras and he has never done anything to them.......He is gentle, sweet and AWESOME to watch! He has never attacked any of our little fish....so I think it just depends on the temperament of the fish. :) david - 2011-06-15 I had a Leopard Bushfish with an African Brown Knifefish and the Leopard Bushfish pestered it nonstop. I eventually had to bring the Leopard Bushfish back to the lfs. jake - 2012-01-13 if the glass catfish is bigger than the tiny ones at petsmart they will most likely do fine and your pleco will be ok. clown loach with be fine to and they get well over 5 inches the perch will be fine for a wile but it might get very big over time Reply

Josh - 2011-03-25 What is the smallest fish that can be kept with african knife fish without getting eaten? Will they eat normal flakes? Click For Replies (4) david - 2011-06-15 Experiment with foods and tankmates until you know. kg - 2011-06-17 You should be fine with most fish. At first they are very timid, but they eventually become more active as said in the article. Mine lives happily in a peaceful 150 gallon aquarium. He is alongside guppies, mollies, upsidown cats, tetras, platys, black ghost knife, gauramis, rasboras, plecos, suckers, boatias, and a betta. My advice would be that they can be kept with anything as long as the take has ample room and he is fed well. They will eat flakes, but they sure do love bloodworms. - kg Vitaly V Kravets - 2011-07-18 Nothing that would be small enough to fit in its mouth like neons or guppys. I would recomend to have it on a blood worm diet or even earth worms that are smaller that you can cut up into chunks work,they like meat! Good luck Dylan - 2011-08-26 My knife fish lives peacefully with guppies mollies platties a gold dojo loach gouramis and a few others in a 50 gallon tank. They are territorial but as long as you keep him well fed he won't bother little guys. Also mine loves earth and blood worms however you can train it to eat flakes or pellets by putting a little garlic juice on them, they love garlic, garlic is generally a flavoring in fish foods. They like meaty foods because they are predators so I would stick with some sort of edible worm Reply

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