The species currently assigned to the South American electric fish genus Porotergus are reviewed. Porotergus duende, a new species, is described from the lowland western Amazon basin in Brazil and Peru. Porotergus gimbeli from the lowland Amazon basin in Brazil and Peru, and P. gymnotus from the Essequibo drainage of Guyana are redescribed. Porotergus duende and P. gimbeli are restricted to deep channel habitats. Porotergus gymnotus occurs in shallow rivers. Notes on the ecology and electric organ discharge of P. duende and P. gimbeli are presented. A key to the members of the genus is provided.