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African Knife Fish
Xenomystus nigri
Also known as African Knifefish, Knife Fish, African Brown Knifefish
Animalia›Chordata›Osteoglossiformes›Notopteridae
The African Knife Fish is a sleek, nocturnal predator with an elongated body and a distinctive knife-like anal fin that runs the length of its belly. Native to West African rivers, this species is relatively peaceful toward larger fish but will consume smaller tankmates. It's an excellent choice for experienced aquarists seeking a unique, active bottom-dweller with interesting behavior.
Where it's from
Native to the Congo, Imo, Kittam, Kwa Ibo and 13 other river basins
Congo - Kinshasa, Nigeria, Sierra Leone, Niger, Sudan, Gabon, Benin, Tanzania and 3 more
At a glance
- Size
- 6 in
- 15 cm
- Min tank
- 55 gal
- 208 L
- Temp
- 75–82°F
- 24–28°C
- pH
- 6.0-7.5
- GH
- 71–143 ppm
- 4–8 dGH
- Temperament
- Semi-aggressive
- Swims
- Bottom
- Lifespan
- 5-8 yrs
Ammonia 0 ppm and nitrate under 20 ppm.
Care
Diet
African Knife Fish are carnivorous and prefer live or frozen foods such as bloodworms, brine shrimp, and small fish. Feed 2-3 times weekly with portions they can consume in a few minutes. They are nocturnal hunters and may be reluctant to eat during the day; offer food in the evening when they become more active.
Behavior
This species is primarily nocturnal and spends most of the day hiding in caves, plants, or dark areas. At night, it becomes an active hunter, using its electrolocation abilities to navigate and find prey in low-light conditions. African Knife Fish are generally solitary and territorial, though they can coexist with larger, peaceful fish that won't fit in their mouths.
Breeding
Breeding in captivity is extremely difficult and rarely achieved in home aquariums. They require specific environmental triggers and large, heavily planted tanks with minimal disturbance. Most specimens in the hobby are wild-caught, making captive breeding impractical for most aquarists.
Tank mates
See all 6Similar size and nocturnal behavior; both are predatory but can coexist with proper space
Compatible nocturnal predator with similar care requirements
Nocturnal bottom-dweller with similar temperament and habitat needs
Nocturnal but smaller; may be viewed as prey if not large enough
Nocturnal armored catfish that can defend itself; similar habitat preferences
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Common diseases 4Ich (Ichthyophthirius multifiliis), Fin Rot, Bacterial Infection, Parasitic Infection
Ich (Ichthyophthirius multifiliis)
White spots on body and fins, rapid breathing, lethargy, rubbing against objects
Increase water temperature to 28-30 C (82-86 F), perform water changes, use ich medication; quarantine affected fish if possible
Fin Rot
Frayed or deteriorating fins, discoloration at fin edges, progressive fin loss
Improve water quality with frequent water changes, remove sharp decorations, use antibacterial medication if severe
Bacterial Infection
Open sores, ulcers on body, cloudy eyes, loss of appetite, lethargy
Perform large water changes, maintain pristine water conditions, use broad-spectrum antibacterial medication
Parasitic Infection
Excessive scratching, visible parasites, weight loss, clamped fins, lethargy
Quarantine affected fish, use antiparasitic medication, maintain optimal water parameters to boost immune system
Legality
No state or federal restrictions on record.
Not legal advice, and possibly incomplete or out of date. Rules vary by state and change over time; check with your state wildlife or agriculture agency before buying, keeping or shipping it.
The care information here is written with AI help, so it can contain mistakes. Spot one? Tell us and we'll fix it. Native range: Tedesco et al. 2017 (CC0).
At a glance
- Size
- 6 in15 cm
- Min tank
- 55 gal208 L
- Temp
- 75–82°F24–28°C
- pH
- 6.0-7.5
- GH
- 71–143 ppm4–8 dGH
- Temperament
- Semi-aggressive
- Swims
- Bottom
- Lifespan
- 5-8 yrs
Ammonia 0 ppm and nitrate under 20 ppm.
Keepers’ experiences
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