This article is about the fish; for the art group, see Inconnu Independent Art Group.

The inconnu or sheefish, Stenodus leucichthys, is a large salmonid fish, related to the whitefishes, found in North America, Europe and the Middle East.

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 green, blue or brown on the back. The meat is white, flaky and somewhat oily.

The fish eat plankton for their first year of life and then become predators of smaller fish. The fish live in lakes and rivers and in the brackish water at the outlets of rivers into the ocean. The fish may migrate 1500 km (1000 miles) to spawn.

An adult fish weighs from 14-25 kg (30-55 pounds).

IUCN lists the inconnu as Endangered.