15 Fin-tastic Facts About The African Knife Fish For Kids

Learn more interesting African knife fish facts here!

The African knifefish is found in the coastal rivers of Africa consisting of the Congo, Nile, Ogooue, and  Chad river basins. These popular species swim around in dim-lit areas underwater. They are not big fans of illuminated open waters. It's identified by many other names such as African brown knifefish, African black knifefish, and so on primarily due to the color of its body. Did you know that the African knifefish (Xenomystus nigri) is the only standing species belonging to the genus of Xenomystus. The African knifefish is considered to be of keen interest to fellow aquarists.

The name "knifefish" is derived from its flat and elongated body making it look like a knife. Knifefish species are often shy in nature however the African brown knifefish is outgoing in comparison. The African brown knifefish is nocturnal and loves swimming around in lightless waters. Its body plays an important role when it comes to hunting for food and navigating dim, shaded areas underwater. This species can grow big in size and therefore require big aquariums. These fishes cannot bend and need lots of space.

If you like reading fish facts, be sure to check out black ghost knifefish facts, or giant guitarfish facts.

African Knife Fish

Fact File

What do they prey on?

Worms, crustaceans, snails, and insects

What do they eat?


Average litter size?

150-200 eggs

How much do they weigh?


How long are they?

11.8 in (30 cm)

How tall are they?


What do they look like?

Blackish, grey-brown

Skin Type


What are their main threats?


What is their conservation status?

Least Concern

Where you'll find them

Freshwater, coastal rivers







Scientific Name

Xenomystus nigri





African Knife Fish Interesting Facts

What type of animal is an African knife fish?

The African knifefish (Xenomystus nigri) is from the Notopteridae family. It's blackish-brown in color with a long body and has an arched back, giving it the look of a knife. They have big eyes which provide them with excellent eyesight. A unique aspect of the African knifefish is that it does not have a dorsal fin, unlike other fishes. The anal fin and caudal fin of the (Xenomystus nigri) are joined which gives it a combined longfin, this remarkable feature makes the African brown knife fish stand out and enhances its swimming pattern.

What class of animal does an African knife fish belong to?

The African knifefish (Xenomystus nigri) is a fish and belongs to the class of Actinopterygii.

How many African knife fish are there in the world?

Often found in freshwater areas, the exact population of the African knifefish is unknown as of now, however, their population is stable and their conservation status is listed as Least Concern.

Where does an African knife fish live?

The African knife fish species are distributed all over tropical Africa which includes the Nile, Chad, Niger, Ogooue, Congo basins as well as coastal rivers in Sierra Leone, Liberia, Togo, Benin, and Cameroon. This relatively large species is well known amongst people.

What is an African knife fish's habitat?

The species of African knifefish (Xenomystus nigri) loves laying low in dim-lit freshwaters that are quiet, preferably with aquatic vegetation. They choose areas of water that don't have a lot of illumination as the knifefish is repelled by it. This is why they are seen to be active only during night times.

Who do African knife fish live with?

African knifefish is solitary in nature, meaning that the (Xenomystus nigri) is often seen swimming around in freshwater habitats by itself. They are territorial in nature. They are aggressive to fishes of their own kind. They can co-exist peacefully with other larger fishes.  

How long does an African knife fish live?

The average life span for African knifefish is three to seven years.  This species can live up to ten years occasionally depending on their diet, which consists of other small fish, snails, worms.

How do they reproduce?

The African knifefish breed in freshwater areas that are quiet preferably with nooks and crannies so these fish can hide. It is during this time one can distinguish between the male knifefish and female knifefish. Females are rounder and more colorful during breeding time. The male knifefish attracts the female by barking sounds. The female often lays around 200 eggs.  

What is their conservation status?

So far, the African knifefish is not threatened by any factors. Their conservation status as of now is listed as Least Concern.

African Knife Fish Fun Facts

What do African knife fish look like?

The African knife fish are quirky, often having a blackish-grey body, their joint underside fin is amusing to the viewer, one might even think it is an alien fish!  Like other knifefish species, they use electrical fields to navigate their way in waters. They have a large mouth and two short barbells through which they feed on small fish at night. A unique characteristic that they possess is to emit a bell-like sound via their swim bladder!

Could not get enough information regarding these fishes? Read more here!

How cute are they?

These fishes don't quite fit the description of cute, however, they are intriguing. These fishes are often shy at first in an aquarium however with some time, they come out of their shell. The African knife fish's size is another reason why one might not find this cute. They are quite large!

How do they communicate?

In aquariums, these fishes make amazing tank mates as long as there is no other knifefish present! They are territorial and nocturnal predators. While breeding, they produce barking sounds to attract females. They also emit a bell-like sound.

How big is an African knife fish?

The African knife fish is large in size. Their size varies depending on their habitat. They are ten times the size of a molly fish! It's necessary that their tank mates in an aquarium are not smaller than them as they will prey on them for food!

How fast can an African knife fish swim?

These fishes can move about 10 cm/s (0.36 kmp/h) while swimming and preying on food! Their diet mostly contains small fishes, snails, worms, crustaceans.

How much does an African knife fish weigh?

The weight of this fish depends on its diet. However, their average weight as of now is unknown.

What are the male and female names of the species?

These fishes don't have any specific names for males and females. They are often referred to as the "female knife" or "male knife"

What would you call a baby African knife fish?

There is no specific name assigned to a baby African knife fish.

What do they eat?

These fishes mainly feed on small fish, shrimps, worms, insects. It is really important that they are not kept with small fish in tanks or in an aquarium. As they would use their large mouths to make those small fish their food!

Are they aggressive?

Yes, these fishes are aggressive to fishes of their own kind. They are very territorial. As long as they are surrounded by larger fishes that won't fit in their mouth, you are good to go!

Would they make a good pet?

Absolutely! These species make really good pets. They are easy to take care of. However, the African knife fish tank size needs to be large. These fishes cannot bend and need lots of space.  

Did you know...

The African knife fish tankmates need to be selected carefully! If you plan on keeping one in your aquarium, ensure there are other large fishes with a similar temperament. They do not like fishes of their own kind.  

A tank of 55 gals (208 l) of water should suffice if you want to provide a healthy habitat for your pet! Often adding shaded areas with plants is essential when it comes to this species, they are repelled by light.

These fish, like most other fish, sleep on their sides!

Why is it called African knife fish?

The name is derived from its long slim body and arched back, which looks like a knife. The African knife fish tank mates would love to have this unique fish around as it is outgoing in nature and will not disturb other fishes!

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these milkfish facts and gulf toadfish facts pages.

You can even occupy yourself at home by coloring in one of our free printable African knife fish coloring pages.



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