Eels are an order of fish which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators. The term "eel" is also used for some other similarly shaped fish, such as electric eels and spiny eels, but these are not members of the Anguilliformes order.
Eels have distinctive life stages. The first is as a larva, then a glass eel, elver, yellow eels, and finally silver eels.
Eels remain relatively unknown from a scientific perspective. Most fish with a high market value have had their genomes picked apart.
The eel is being increasingly harvested for food. The young elvers can fetch a world market price of up to $600 per pound.
American eels range from Greenland to South America, occurring in all major streams along the coastline. The females migrate far inland, and have been documented in nearly all states east of the Rocky Mountains.
As Eels grow, they become darker and are known as elvers. They’re still very small, reaching a length of only about 5 inches after a year in fresh water. Most elvers migrate upstream, as far as 600 miles, but some remain in estuaries.
Eels are very successful scavengers that take advantage of habitats other fishes cannot utilize. Young eels feed mainly on insects and small crustaceans.
Eels are nocturnal, buried in mud, sand or gravel during daylight hours and eat fish, invertebrates, carrion, insects, worms and amphibians. An eel is generally female if its length exceeds 18 inches, as males tend to average much smaller lengths, typically 8 to 12 inches.
The eel lives primarily in fresh water and is thought only to leave for the Sargasso Sea to spawn between February and July. Approximately 15 to 20 million eggs are released at that time and after hatching, drift in the sea for a year before becoming glass eels, move toward North America to enter freshwater systems and develop pigmentation, turning yellow before becoming silver.
American eels have a large distribution that includes the North American east coast and extends down to South America. They are classed as catadromous fish, which means that on attaining sexual maturity, adult eels migrate downstream to the sea where ultimately they spawn.
American eels can be described as having a long, snake-like body structure. They have a dorsal fin that extends along the last third of their body.