Which freshwater fish species produces the highest measured electric discharge, reaching about 860 volts?

Electrophorus voltai is the freshwater fish species recorded producing an electric discharge of about 860 volts.

The species belongs to the electric eel genus Electrophorus, although electric eels are knifefish rather than true eels. It lives in South American rivers and uses electricity both to locate prey and to defend itself. Its powerful organs are modified muscle tissues that generate electrical pulses.

The 860-volt measurement was reported after Electrophorus voltai was identified as a separate species in 2019. Before that discovery, scientists generally treated electric eels as one species, Electrophorus electricus. The other recognized species, Electrophorus varii, is associated with lower-voltage discharges.

Electric eels must surface regularly because they breathe air, despite spending most of their lives in water. Their ability to generate electricity is therefore a biological adaptation, not evidence that they are closely related to marine eels.