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African Knife Fish
Xenomystus nigri
📍 West Africa
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.
Care Guide
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
Similar 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
Aggressive cichlid; only suitable if African Knife Fish is significantly larger
Common Diseases
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
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Quick Facts
- diet
- Carnivore - feeds on small fish, shrimp, and meaty foods
- lifespan
- 5-8 years
- max size
- 15 cm (6 in)
- tank size
- 55 gallons minimum
- temperament
- semi-aggressive
Water it likes
- ph
- 6.0-7.5
- ammonia
- 0 ppm
- nitrate
- <20 ppm
- hardness
- 4-8 dGH
- temperature
- 75–82°F (24–28°C)