Smelt (Osmeridae) is a genus of fish in the smelt family. The European smelt (Osmerus eperlanus) inhabits the basins of the White, Barents and Baltic Seas. It is a passable and lake fish. Length 15-25 cm, weight up to 40 g. 2 subspecies, within Russia one subspecies O. mordax dentex. The Asian toothy smelt (Osmerus mordax) differs from the European smelt by its large size - up to 35 cm and weight up to 350 g, longer lateral line and more developed teeth. It lives in the basins of the White and Barents Seas and along the Asian coast up to the Korean peninsula. Passable fish. Smelt are commercial fish.

Smelt are small, slender fish with a dark back and silvery sides and belly. The dorsal fin is short, contains 7-14 rays, and is located in the middle of the body, above the pelvic fins. The caudal fin has 19 rays, the pelvic fin has 7-8 rays. On the maxillary bones are teeth. The stomach in most species in the form of a blind bag. There is a swim bladder. The lateral line is incomplete. Many smelt are characterized by a specific smell of fresh cucumbers, for which the smelt is also called "cucumber".

Smelt are gregarious fish living in the bottom layers or in the water column. At a young age they feed on planktonic crustaceans, adult fish in some species (capelin) continue to feed on plankton, in others - switch to feeding on bottom crustaceans, worms and small fish. Smelt eggs are bottom-feeding, adhesive; egg size is 0, 7-1, 1 mm.

Smelt are widely distributed in the northern hemisphere. They inhabit marine and fresh waters of the basins of the northern parts of the Atlantic and Pacific Oceans and the Arctic Ocean. Among the smelt species, some species spend their entire life in the sea (capelin, allosmer), while others spend part of their life in the sea or in pre-mouth areas of rivers, in brackish water, and enter rivers for reproduction (common smelt, smallmouth smelt, spirinhas, taleicht), and some of them can live in fresh water bodies, forming living forms (lake smelt, snets).

There are a total of 6 genera and about 10 species in the smelt family.