The electric eels are a genus, Electrophorus, of tropical freshwater fish from South America in the family Gymnotidae. They are electric fish, and can stun their prey by delivering shocks at up to 860 volts. Their electrical capabilities were first studied in 1775, contributing to the invention in 1800 of the electric battery. Despite their name, they are not closely related to the true eels (order Anguilliformes) but are electroreceptive knifefish (order Gymnotiformes), more closely related to catfish. Previously, the genus was believed to be monotypic, containing only Electrophorus electricus. In 2019 it was discovered that there were three species. They are nocturnal, air-breathing animals, with poor vision complemented by electrolocation; they mainly eat fish. Males are larger than females. Electric eels grow for as long as they live, adding more vertebrae to their spinal column. Some captive specimens have lived for more than 20 years. (Full article...)