The dietary habits of the Oligocene fish Scopeloides glarisianus (Agassiz) are presented on the basis of functional morphology, in comparison with their recent relatives (Gonostoma spp.) as well as fossil materials from localities in Poland (Lubenia, Błażova), Ukraine (Ljubizhnja), the Czech Republic (Loučka), and the northern Caucasus in Russia and Abkhazia. Analogous to the recent relatives from the genus Gonostoma, S. glarisianus fed on crustaceans such as ostracods and copepods, the larger specimens preying on small fishes. Fishes remains preserved within the alimentary canal region are usually represented by smaller individuals of the same species; accordingly, the cannibalistic behaviour of the adult S. glarisianus is thereby documented. The remains of the alimentary canal and the peritoneum are identified.