Contribution to the occurrence of parasites in Cobitis elongatoides and Cobitis elongatoides x C. sp.

In the Nova Rise valley reservoir (River Dyje drainage area), we observed a high intensity of infection in Cobitis elongatoides by the tapeworm Ligula colymbi plerocercoids. Of the samples caught in spring 1996, 7.1 % of C. e longatoides males and 19.5 % of females examined were infected. In infected C. elongatoides specimens, gonad atrophy was also observed. In 1995 and 19 99, we observed one specimen of C. elongatoides infected by L. colymbi each year. Within the lower River Dyje floodplain in autumn 1998, metacercariae of the trematode, Posthodiplostomum cuticula was found in 73 % of the memb ers of the genus Cobitis (hybrids C. elangatoides x C. sp.).