The topmouth gudgeon is an invasive species of the European fish fauna that causes problems not only as a competitor of native fishes in natural waters but also generates damages
in pond fish farming. The behaviour of topmouth gudgeon has already been studied from a number of aspects, however, complex investigations on the habitat use of the species in invaded regions were not carried out yet. Here the habitat use of the fish in a close-tonature pond system was examined with special, non-selective minnow traps and observations were subsequently complemented by aquarium experiments. Our findings revealed
that in a pond inhabited by predator fish, topmouth gudgeon preferred the pelagial region, while in a pond free of predator fish, they preferred the littoral zone. The examined abiotic
parameters had no effect on the habitat use of the fish. In a simplified artificial environment experiments have yielded the same results. The findings showed that topmouth gudgeon is rather flexible in adapting to the environmental conditions, the available nutrition base, but from the aspect of habitat use the most significant factor is probably the presence of predatory fish. The results can establish an effective suppression method of topmouth gudgeon populations with predator fishes
