Gymnotus

Gymnotus is a genus of fish in the order Gymnotiformes found widely in the Neotropics, including the Amazon. Some Gymnotus species live in the leaf litter and root tangles of river banks. Other species are specialized to live on floodplains within the rootmats of floating meadows. Several species are broadly adapted to live in both of these habitats. Gymnotus species are nocturnal predators feeding on insects, crustaceans, and other fish. They generate weak electric fields used in locating objects, and also for communication in which the males court females using stereotyped electrical "songs".