The modified immune response, shifted ecology, inheritance, and maternal ancestry of hybrid host fish are supposed to affect the diversity of their parasite communities. The pattern of metazoan parasite distribution in species with different morphology and ecology harbouring different specific parasites (i.e. common bream (Abramis brama), roach (Rutilus rutilus)- and their hybrids) and temporal and spatial aspects as possible factors influencing parasite distribution were analysed. Observed asymmetrical distribution of parental species-specific parasites in hybrids may suggest the limited inheritance of protective immunological mechanisms from one parental species and reveal stronger coadaptation between common bream and its specific parasites.