Gyrodactylus proterorhini Ergens, 1967 (Monogenoidea, Gyrodactylidae) in gobiids from the Vistula River--the first record of the parasite in Poland.

During a parasitological survey of two non-native fish species-racer goby Neogobius gymnotrachelus and monkey goby Neogobius fluviatilis-in the Włocławek Reservoir on the lower Vistula River, the monogenean Gyrodactylus proterorhini was recorded for the first time in Poland, and for the first time, the racer goby was listed as the parasite host. Specimens of G. proterorhini were detected on body surface, fins, and gills of the fish studied. In 2006, the monkey goby was infected with the prevalence 41%, racer goby with the prevalence of 47%, at maximal intensity of 6 and 9 parasites per fish, (respectively). The infection level in relation to the fish size and sampling season was also discussed. The presented study supports the hypothesis of progressive introduction of the parasite with gobiids to the colonized areas.