Roughly four-fifths of an electric eel's body is given over to three electric organs built from stacked cells called electrocytes. Discharged together, they produce pulses that have been measured at several hundred volts in large individuals.
Laboratory work by Kenneth Catania showed that the eel's high-voltage volley does not merely shock; it stimulates the efferent motor neurons of a nearby fish, causing an involuntary tetanic contraction that freezes the prey. Before striking at concealed prey, the eel emits pairs of pulses that trigger a twitch, and the resulting water movement betrays a hidden fish. The eel also curls its body to bring head and tail closer together, concentrating the field on the target.
The genus turned out to be more than one species: a 2019 study split Electrophorus into three, with Electrophorus voltai recorded at up to about 860 volts. How often the highest discharges occur in the wild, and what limits them, remains poorly documented.