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. Their electrical capabilities were first studied in 1775, contributing to the invention in 1800 of the electric battery.
Despite their name, electric eels are not closely related to the true eels (Anguilliformes) but are members of the electroreceptive knifefish order, Gymnotiformes. This order is more closely related to catfish. In 2019, electric eels were split into three species: for more than two centuries before that, the genus was believed to be monotypic, containing only Electrophorus electricus.
They are nocturnal, obligate air-breathing animals, with poor vision complemented by electrolocation; they mainly eat fish. Electric eels grow for as long as they live, adding more vertebrae to their spinal column. Males are larger than females. Some captive specimens have lived for over 20 years.
When the species now defined as Electrophorus electricus was described by Carl Linnaeus in 1766, based on early field research by Europeans in South America and specimens sent back to Europe for study, he used the name Gymnotus electricus, placing it in the same genus as Gymnotus carapo (the banded knifefish). He noted that the fish is from the rivers of Surinam, that it causes painful shocks, and that it had small pits around the head.
In 1864, Theodore Gill moved the electric eel to its own genus, Electrophorus.
The name is from the Greek ήλεκτρον ("", amber, a substance able to hold static electricity), and φέρω ("", I carry), giving the meaning "electricity bearer". In 1872, Gill decided that the electric eel was sufficiently distinct to have its own family, Electrophoridae. In 1998, Albert and Campos-da-Paz lumped the Electrophorus genus with the family Gymnotidae, alongside Gymnotus, as did Ferraris and colleagues in 2017.
In 2019, C. David de Santana and colleagues divided E.