Smelts are a family of small fish, the Osmeridae, found in the North Atlantic and North Pacific oceans, as well as rivers, streams and lakes in Europe, North America and Northeast Asia. They are also known as freshwater smelts or typical smelts to distinguish them from the related Argentinidae (herring smelts or argentines), Bathylagidae (deep-sea smelts), and Retropinnidae (Australian and New Zealand smelts).

Some smelt species are common in the North American Great Lakes, and in the lakes and seas of the northern part of Europe, where they run in large schools along the saltwater coastline during spring migration to their spawning streams. In some western parts of the United States, smelt populations have greatly declined in recent decades, leading to their protection under the Endangered Species Act. The Delta smelt (Hypomesus transpacificus) found in the Sacramento Delta of California, and the eulachon (Thaleichthys pacificus) found in the Northeast Pacific and adjacent rivers, are both protected from harvest.

Some species of smelts are among the few fish that sportsmen have been allowed to net, using hand-held dip nets, either along the coastline or in streams. Some sportsmen also ice fish for smelt. They are often fried and eaten whole.

The earliest known fossil smelt is Enoplophthalmus from the Early Oligocene of Europe; Speirsaenigma from the Paleocene of Canada may be an even earlier representative, although some authors instead consider it a relative of the ayu.

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