The electric eel is a South American electric fish. Despite the name, it is not an eel, but rather a knifefish.
The electric eel has an elongated, cylindrical body, typically growing to about 2 m in length, and 20 kg in weight, making them the largest species of the Gymnotiformes. Their coloration is dark gray-brown on the back and yellow or orange on the belly. Mature females have a darker color on the abdomen. They have no scales. The mouth is square, and positioned at the end of the snout. The anal fin extends the length of the body to the tip of the tail.
The electric eel has three pairs of abdominal organs that produce electricity: the main organ, the Hunter’s organ, and the Sach’s organ. These organs make up four fifths of its body, and give the electric eel the ability to generate two types of electric organ discharges: low voltage and high voltage. These organs are made of electrocytes, lined up so a current of ions can flow through them and stacked so each one adds to a potential difference. In the electric eel, some 5,000 to 6,000 stacked electro-plaques can make a shock up to 600V and up to 1A of current. This level of current is reportedly enough to produce a brief and painful numbing shock like a stun gun discharge, which due to the voltage can be felt for some distance from the fish.
Electric eels feed on invertebrates, although adult eels may also consume fish and small mammals, such as rats. First-born hatchlings eat other eggs and embryos from later clutches. The juveniles eat invertebrates, such as shrimp and crabs.
The electric eel is known for its unusual breeding behavior. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 3,000 young hatch from the eggs in one nest. Males grow to be larger than females by about 35 cm.