The fins are peculiar to this fish with paired, bluntly rounded pectorals and a single continuous dorsal, caudal and anal fin. The eel prefers fairly deep, mud-bottom waters, which probably accounts for the reason they are most often found in the larger rivers. Weight rarely exceeds a couple of pounds, but some individuals, especially if landlocked, may reach a maximum of 5 to 6 feet and weigh l0 to l5 pounds. Eels, because of their snakelike movements, are able to navigate in extremely shallow marshy areas. They are largely nocturnal feeders consuming mainly fish, invertebrates and terrestrial organisms that are washed into the water.
Eels are carnivores and, contrary to earlier thinking, seek living rather than dead organic matter.
The spawning life cycle of the American eel is endemic to this species. Eels are catadromous, which means they spawn in saltwater and mature in freshwater. The cycle begins with the female maturing in freshwater streams over a period lasting from 5 to 20 years. Upon maturity they migrate downstream to the sea in autumn. Females are joined by the males, which have remained in the estuaries, never growing much more than 2 feet in length.