Smelts are found in north temperate and frigid waters in North America, Asia and Europe. Most species are marine or anadromous and only one species is found in New York's freshwater. It is distinguished by the presence of an adipose fin, a lack of a pelvic axillary process, and the presence of a prominent lateral silver stripe. They also have large teeth on their tongues. Rainbow smelt is anadromous and occurs in coastal streams, the Hudson and Saint Lawrence Rivers and in Lake Champlain. Several inland, land-locked populations exist as well, most the result of introductions.
Rainbow Smelt is anadromous as a coastal species and it has many landlocked populations in large lakes. Native watersheds include the Lower Hudson, Long Island and Champlain, while it also occurs in 13 others, or all but Allegheny and Chemung.