Anguilla rostrata

American eels are slender and snakelike with slippery skin that appears to lack scales. They have a yellowish to brown body with a white to pale yellowish belly and a small, reddish, pointed head. Their lower jaw protrudes beyond the upper jaw. Their long dorsal fin is continuous with the tail and anal fins. These eels have a small, single gill slit on each side in front of their pectoral fin. They can reach a total length of up to 60 inches (152 cm).
 

American eels spawn in the Atlantic Ocean. Their coastal range extends from southern Greenland (small populations), Labrador, and Newfoundland southward along the Atlantic coast of North America to southern Florida, and along the coast of the Gulf of Mexico to the northern tip of the Yucatan Peninsula, the Caribbean coast of Central America, the Caribbean and Atlantic coasts of the Greater and Lesser Antilles and other West Indies islands, and occasionally the northern portion of the Atlantic coast of South America. 

As part of their native distribution, American eels penetrate far inland in many areas, such as Lake Ontario via the St. Lawrence River, Grand Matagamon Lake at the head of the East Branch of the Penobscot River in Maine, Rangeley Lakes at the head of the Androscoggin River in Maine, the headwaters region of the Connecticut River in New Hampshire, the upper Mississippi River basin to South Dakota, Minnesota (including the Wisconsin River as far as Prairie du Sac Dam), and Pennsylvania, and New Mexico in the Rio Grande Basin. In New York, eels historically penetrated inland throughout much of the state, except the far western end that is west of the Finger Lakes region. Construction of canals in the Great Lakes region has allowed expansion of the range of the American eel. This species has been introduced (stocked, released, escaped) in several inland areas, such as the Great Lakes region and several areas in the western United States.
 

American eels spawn in the Sargasso Sea, a large area in the western Atlantic Ocean east of the Bahamas and south of Bermuda. Larvae drift and swim in prevailing currents that take them to areas near the coast. They then reach life stages known as glass eels and elvers, and enter estuaries and streams. Some elvers turn yellow and travel upstream to spend the majority of their life in rivers, streams, ponds, and the shallow, more productive areas of lakes. Other eels remain in estuaries for their entire development prior to migrating back to the ocean.

The timing and duration of upstream migration by young eels varies with location and may occur from March through October, with a peak in May, June, and July in many areas (July-August in the St. Lawrence River). They may migrate upstream for months or years. They typically begin their downstream migration to their spawning areas in the ocean in summer or fall in northeastern United States.