Xenomystus Nigri

Xenomystus nigri is the sole species of its genus within the family Notopteridae and the only knife fish native to Africa outside of the Nile. Its long, laterally compressed body tapers to a point at the tail, and it propels itself exclusively via the long, undulating anal fin — a movement style that allows it to swim both forwards and backwards with equal ease. It generates a weak electric discharge for communication and navigation.

In the aquarium, the African Knife Fish is primarily nocturnal and requires extensive hiding opportunities: large PVC pipes, terracotta caves, and driftwood tangles are all ideal. Dim lighting or a gradual dimming cycle encourages more visible daytime activity. It can be housed singly or in small groups if the tank is large enough and hiding spots are abundant.

Feeding Xenomystus nigri requires patience — frozen bloodworm, earthworm, and live invertebrates should be presented near its hiding place after lights dim. With time, individuals often learn to associate the keeper's presence with feeding and become more bold. It is peaceful with species too large to swallow.

Water: Soft to moderately hard, pH 6.0–7.5, temperature 23–28°C, GH 2–15, KH 1–8. Tank: Minimum 200 L, large PVC pipes and caves, dim lighting, fine sand substrate. Feeding: Carnivore; frozen bloodworm, earthworm, small prawns, and tubifex; feed at night. Breeding: Egg guarder; male guards eggs laid on flat surface; soft acidic water triggers spawning. Compatibility: Peaceful with species too large to swallow; predatory toward small fish and invertebrates.