Inter-population variability of diet of the alien species brown bullhead (Ameiurus nebulosus) from lakes with different trophic status.
The alien fish species brown bullhead (Ameiurus nebulosus) has had a direct impact on native fish species through competition for food and predation in European water bodies. The aim of the study was to determine the diversity, frequency of occurrence and abundance of types of food in the stomachs of 278 individuals of A. nebulosus from seven lakes in Central-Eastern Europe with different trophic status. Altogether, 20 types of food (including taxa) in the diet of A. nebulosus were found and the most frequently eaten were detritus, Chironomidae, plants and selected taxa of macrofauna. In the diet of fish from lakes with higher trophic status the higher share of detritus and the lower number of type of food were noted. Fish in the diet were present only in brown bullhead from two lakes, but in the other lakes in the diet, fish scales were reported. The present study shows that A. nebulosus in the lakes of Central-Eastern Europe is an opportunist and the composition of its diet is strictly dependent on habitat. In addition, due to its flexibility, this alien species can easily adapt its food preferences to potential food resources in occupied water bodies.