Norbert Wu / Electric Eel (Electrophorus electricus) can generate up to 220 volts, freshwater, Steinhart Aquarium, San Francisco, California

Mark Bowler / Electric eel (Electrophorus electricus) on white background. Controlled conditions, digital focus stack.

Mark Bowler / Electric eel (Electrophorus electricus) swimming towards the surface to breathe, Yavari area, Amazon Rainforest, Peru.

Joel Sartore / Photo Ark / Electric eel (Electrophorus electricus), close-up of head. Oklahoma Aquarium. Captive.