A fish fauna from a Turonian sequence of the Great Bear Basin at Lac des Bois is described. The fauna includes examples of Ichthyodectes, cf. Osmeroides, a euteleost, and several aulopiforrn fishes such as Enchodus, Cimolichthys, and a juvenile that cannot be further identified. The fauna of Lac des Bois most closely resembles other Arctic fish assemblages of the Western Interior Seaway based on a UPGMA (unweighted pair-group method with arithmetic averages) cluster analysis of various North American Turonian localities. There are also slight differences between eastern and western localities along the seaway. The north–south differences of the ichthyofauna can be explained by current patterns distributing the fishes in the seaway, or transgressive events during the Turonian. The east–west differences may be due to changes in water depth from east to west.