EFFECT OF MATERNAL ORIGIN ON MONOGENEAN INFECTION IN FISH HYBRIDS V. KRASNOVYD AND A. VETEŠNÍKOVÁ ŠIMKOVÁ Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlařská 2, Brno, 611 37, Czech Republic The close affinity to a single host species for some parasite species (termed as highly host specific) such are monogeneans is predicted in link with host-parasite coevolution. However, hybridization may interrupt the system of co-adaptation genes. Recently, there is limited information concerning the effect of maternal origin on parasite infection in hybrids. In our study, common bream (Abramis brama), roach (Rutilus rutilus) and their respective hybrids from Hamry reservoir (Czech Republic) were collected in spring and autumn 2011, and investigated for the presence of metazoan parasites. Identification of the fish individuals was performed using morphological characters and molecular diagnostic based on the sequence analysis of mitochondrial DNA – partial cytochrome b gene. The aim of this study was to compare monogenean infection between two parental species and hybrids with different maternal origin. Diversity of monogenean communities was higher but parasite abundance was lower in hybrids where compared to parental species. Regarding maternal origin of hybrids the predominance of individuals with common bream maternal origin was found. The potential effect of maternal origin on parasite infection in hybrids was analyzed.