The electric eels are a genus, Electrophorus, of neotropical freshwater fish from South America in the family Gymnotidae. They are known for their ability to stun their prey by generating electricity, delivering shocks at up to 860 volts.
Despite their name, electric eels are not closely related to the true eels (Anguilliformes) but are members of the electroreceptive neotropical knifefish order (Gymnotiformes), which is more closely related to the catfish.
For over two centuries, the genus was believed to be monotypic, containing only Electrophorus electricus, until the unexpected discovery in 2019 of two additional species. E. varii is a lowland species of water bodies of depths that vary with the season; it reproduces in the dry season and provides months of parental care to its young.
E. electricus and E. voltai are upland species of fast-flowing rivers, providing much less parental care.
The electric eel's electrical capabilities were studied by Hugh Williamson and John Hunter in 1775, contributing to the 1800 invention of the electric battery.
Three pairs of electric organs are arranged along the body, enabling the fish to generate both low voltage discharges for electrolocation, and high voltage discharges to stun prey or to defend themselves.
Electroreceptors are distributed around the body in the skin; this enables them to detect the electric signals of other Gymnotiform fish, which they hunt.
Electric eels grow as long as they live, adding more vertebrae to their spinal column; males are larger than females. In aquaria, they can live for at least 20 years.