For a long time scientists thought electric eels hunted alone. Then, in a small lake in northern Brazil, they found more than 100 adult electric eels together. In Brazil, groups of electric eels were seen herding small fish into a tight ball, and then smaller groups of up to 10 eels sent out shocks together. An electric eel eats fish and other small animals, and its electric shock stuns the animals it eats. Young electric eels eat mostly small animals without backbones, such as insects and crustaceans, and adults eat mostly fish.
An electric eel makes electricity with special cells called electrocytes, and it has thousands of them. The electrocytes work like a stack of batteries. An eel's electric organ is made of hundreds of thousands of flat cells connected in a line, like a long string of battery cells. An electric eel has three electric organs, and most of its body is electric organ. The two larger organs, called the Main and Hunter's organs, make the strong shock, and the small Sachs organ makes the weak pulses. The shock works on the nerves of the eel's food, which makes the muscles tighten.
Electric eels hunt at night, and an electric eel does not see well. Most of the time it makes only a weak charge, about 10 volts or less, to find its way and to find prey. At rest an eel gives off very little electricity, and it gives off more when it moves around or feeds. It also has a line of motion-sensing hairs along its body, called the lateral line, that feels tiny changes in the water. When an eel thinks food is nearby, it sends out two quick pulses called a doublet, and the doublet makes hidden fish twitch. After the shock, the eel opens its mouth to make suction and takes in its food. Electric eels use weak electric pulses to talk to each other.
For about 250 years scientists counted only one kind of electric eel. As of November 2026, they know of at least three species. The three kinds look much alike, so a scientist used their DNA to tell them apart. The electric eel was first described by the scientist Carl Linnaeus in 1766. One of the new species is named Electrophorus varii for the late Smithsonian fish scientist Richard Vari, and another is named E. voltai for Alessandro Volta. An electric eel is a fish, but it is not a true eel. It is more closely related to catfish and carp than to true eels.
In a burst of shocks, an electric eel can send out as many as 400 pulses a second. The shock is high in voltage but low in current, about one amp. The bigger an electric eel is, the stronger its discharge. An electric eel grows to be about 8 feet, or 2.5 meters, long, and as of November 2026 the heaviest published weight is 20 kilograms (44 pounds). As of November 2026, scientists have measured a shock of 860 volts from one Volta's electric eel, the strongest discharge known from any living animal. That is higher than the 650 volts that had been cited before for electric eels.
Electric eels live in rivers and ponds in South America, in quiet, slow-moving, muddy water in the Amazon and Orinoco river basins. An electric eel has gills like other fish, but it cannot live without air, and the water where electric eels live can be muddy and low in oxygen. An eel has to come to the surface for a breath at least every ten minutes, and it gets about 80 percent of its oxygen by gulping air at the surface. In the dry season the water in the rivers drops, and electric eels can be left in small pools. When the rainy season comes and the rivers swell, young electric eels spread out into new areas.
Words to know
- electrocytes: power cells
- doublet: two quick pulses
- current: flow of electricity
- herding: gathering together
- suction: pulling force
