Several specimens of a new knife-fish, Distocyclus guchereauae, belonging to Sternopygidae (Gymnotiformes), were caught in two tributaries (Litany and Tampoc) of Maroni river (French Guiana). This species differs from the other Distocyclus by having 13-14 versus 11-15 precaudal vertebrae, a small number of anal fin rays (184-187 versus 160-260), a triangular head with a short snout and a terminal mouth, and the anus located straight below the eyes.