Stenodus nelma, known alternatively as the nelma, sheefish, siifish, inconnu or connie, is a commercial species of freshwater whitefish in the family Salmonidae.

[2][1][3][4] Stenodus nelma is an anadromous fish, up to 150 centimetres (59 in) in length.

[4] The fish has a large mouth with a protruding lower jaw and a high and pointed dorsal fin.

It is generally silver in color with a green, blue or brown back.

The typical Stenodus leucichthys (beloribitsa) is a landlocked Eurasian species restricted to the Caspian Sea basin, and now extinct in the wild.