[Parasites in sea and fresh water fishes]

A total of 429 individuals of three fish families: Clupeidae, Cyprinidae and Percidae were subjected to parasitological investigation. All fishes were from retail shops were they had been kept frozen. The parasites found belong to the groups Monogenea, Trematoda, Cestoda, Nematoda, Acanthocephala, Hirudinae and Crustacea. Almost all endoparasites were localized in the intestines, the ectoparasites on the gills or on the skin. The fishes investigated were slightly infected, but suitable for consumption. The majority of different species of parasites was found in fishes that shoal, which is quite concordant with "Janiszewska's rule".