Gnathonemus is a genus of African weakly electric fish in the elephantnose family, Mormyridae, distributed across rivers and floodplains of Central and West Africa. Its defining feature is the elongated, flexible chin extension — the "Schnauzenorgan" — a mobile, highly sensitive probe covered in electroreceptors that the fish uses, together with a weak electric organ in its tail, to navigate and locate prey in murky or turbid water by night. Species in the atlas range from about 4.5–14 in, and all are nocturnal, secretive fish that shelter in cover by day and forage over soft substrate after dark.
The best-known member of the genus, Gnathonemus petersii, sold as Peter's elephantnose, is a long-standing aquarium favorite prized for its unusual anatomy and for a level of apparent intelligence and social behavior unusual among aquarium fish, linked to a cerebellum that is proportionally very large for its body size. It is also a genuinely demanding fish to keep — sensitive to poor water quality, needing soft, dim, well-covered tanks and live or frozen foods, and prone to injuring its sensitive chin organ on rough decor. Conservation status across the genus is reasonably favorable: three of the five species in the atlas are Least Concern, with one Data Deficient and one not yet evaluated.