What is "gymnarchus"

Gymnarchus niloticus – commonly known as the aba, aba aba, frankfish, freshwater rat-tail, poisson-cheval, or African knifefish – is an electric fish, and the only species in the genus Gymnarchus and the family Gymnarchidae within the order Osteoglossiformes. It is found in swamps, lakes and rivers in the Nile, Turkana, Chad, Niger, Volta, Senegal, and Gambia basins.