Mormyrid fish Feeding habits Guinea Republic Dietary patterns of Brienomyrus brachyistius (Gill, 1862) in Tinguilinta and Kogon rivers were described. Diets composition and feeding strategy were analyzed among hydrosystems based on the stomach content analysis. The diets compositions were similar in the two rivers and essentially composed of insects larvae (Diptera, Coleoptera, Ephemeroptera and Trichoptera) and insects debris. Brienomyrus brachyistius exhibited a generalist feeding strategy with a relatively narrow niche width in the two rivers as there was a trophic specialization by many individuals toward Trichoptera larvae. Apart from insects, seeds and sand were found in many stomach contents. The ontogenetic analysis of diet indicated that there were not size-related changes in the diet of the studied species.