Gymnotiformes

Gymnotiformes is an order of Neotropical freshwater fishes known for their ability to generate electricity. Members are commonly called knifefishes and include the electric eel (Electrophorus electricus). They range from southern Central America to much of South America, with many species residing in river systems such as the Amazon and Orinoco basins. Morphologically, gymnotiforms are elongated and generally lack paired fins; they propel themselves with a long anal fin that undulates along the body, yielding a ribbon-like form.

Most gymnotiforms are weakly electric, generating low-voltage electric organ discharges (EODs) used for active electrocommunication and electrolocation in murky water. The electrical signals help them navigate, locate prey, avoid obstacles, and attract mates. The notable exception is the electric eel, Electrophorus electricus, which can emit high-voltage shocks up to several hundred volts for predation and defense.

Habitat and conservation: They inhabit a variety of freshwater habitats, including rivers, swamps, and floodplains, often in vegetated or turbid waters. Because they rely on electric sensing, water clarity is less critical than ambient noise and conductivity. Many species face threats from habitat destruction, pollution, and overfishing; some have restricted distributions and are of conservation concern. Research on Gymnotiformes contributes to understanding bioelectricity, neural control of movement, and sensory biology.