Freshwater eels are fish, and belong to the family Anguillidae. Slow growing and long lived, they begin life in the sea, and then spend many years in fresh water as adults. Finally they return to sea to spawn, after which they die.
Do they bite?
Many people are scared of eels, because they are snakelike and slimy, and can slither over land. There are very few reports of eels attacking, but if they do, their teeth can grip. In one incident a longfin eel bit the wetsuit of a diver, who had to use a knife to release its hold.
Unlike nearly all other freshwater fish, eels have a long cylindrical shape, and continuous dorsal (back), caudal (tail) and anal fins. They have pectoral (side) fins but no pelvic fins.
Covered in a layer of mucus, eels are extremely slippery. Although they seem to lack scales, under the microscope you can see a mosaic of tiny scales in the leathery, slimy skin.
Eels can travel over land, slithering through wet grass to get to a pond or lake. As long as their skin stays moist they can absorb oxygen through it, surviving long periods out of water.
Occasionally people find an albino (yellow or white) eel. These ones don’t have the usual dark colouring on their backs for camouflage, and the yellow or white pigment shows up clearly in the water. They often don’t last long in the wild, as birds overhead spot them easily.
Freshwater eels are found worldwide. Of 15 recognised species, most occur in the waterways that flow into western Pacific and Indian oceans. There are none that spawn in the eastern Pacific or the South Atlantic.