Electrophorus is the electric eel genus - not a true eel at all, but a member of the South American knifefish order Gymnotiformes, distantly related to the weakly electric knifefishes kept in the hobby. The atlas' 3 species (E. electricus, E. varii and E. voltai) live across the Amazon and Orinoco drainages of Brazil, the Guianas and Venezuela, in slow, oxygen-poor floodplain waters and blackwater creeks. What was long treated as a single wide-ranging species has more recently been split apart based on habitat, ecology and the strength of the fish's electric discharges.
Electric eels are unmistakable: long, scaleless, eel-like bodies that in the atlas run from roughly 58.5–98.5 in, most of the body given over to specialized electric organs used both to stun prey and to deter predators. They are also obligate air-breathers, gulping atmospheric oxygen through a heavily vascularized mouth lining that lets them survive in water too poor in oxygen for most other fish. All three species are currently assessed Least Concern, but their size, power and specialist care needs keep them almost entirely in public aquariums and research collections rather than home tanks.