Knifefishes are found in the Old World (Africa, Asia) and in the New World (South and Central America). However, the two groups are not closely related. Aquaristically, however, they are quite comparable. They inspire above all by their elegant swimming. The very special fin structure allows them to maneuver both forward and backward. At the same time, they are lightning fast. And knifefish are intelligent – at least by fish standards. They get to know the keeper and come to receive tidbits on whistle. Among themselves, they communicate with sounds and “electric speech,” which uses weak electrical impulses.
The smallest species of Old World knifefish is Xenomystus nigri, which usually grows to 12-15 cm, exceptionally to 20 cm. It is widely distributed in western Africa; the photographs show a juvenile specimen from the Congo and two adults from the Niger River in Nigeria, from where we usually obtain them. X. nigri can be very easily distinguished from all other Old World species by the fact that it lacks a dorsal fin, all other species have one.
Very small fish become eaten by African knifefish, they are peaceful to all larger fish. They are crepuscular animals, as can be easily seen from their large eyes. In the aquarium Xenomystus do not necessarily want caves, but dim shelters. The sexes are hardly distinguishable, males are a bit more high-backed. Xenomystus nigri are crevice spawners, “shooting” their eggs individually into depressions or small holes. The species does not seem to take broodcare.
Xenomystus nigri feeds in nature mainly on insects and worms. In the aquarium, it readily accepts all common frozen foods, but will also accept dry foods. Although the fish is not colorful, it is a wonderful contrast fish to other aquarium inhabitants, it is, as we say, the salt in the soup.
For our customers: the animals have code 192004 on our stock list. Please note that we supply exclusively to wholesalers.
Text & photos: Frank Schäfer