Variation in Parasite Infracommunies of Tilapia zillii in Relation to Some Biotic and Abiotic Factors

This study analyzed the variation in the parasite infracommunities of T. zillii and their relationship with host origin, host sex and host size. A total of 290 (142 wild fish and 148 cultured fish) Tilapia zillii were collected from lake Manzalah, Egypt, from July to September during 2010. Parasite community of wild and cultured, T. zillii consisted of 12 species, one protozoon (Trichodina spp.), eight monogenea (Cichlidogyrus arthracanthus, C. aegypticus, C. sclerosus, C. halli typicus, C. tilapiae, C. ergensi, C. tiberianus and Gyrodactylus cichlidarum), one acanthocephalan (Acanthogyrus tilapiae) and two crustacean species (Lernaea cyprinacea and Ergasilus sp.). The most prevalent parasite was C. arthracanthus (47.94%) and C. aegypticus (33.82%) while the less prevalent one was C. sclerosus (9.12%) in both wild and cultured fishes combined. The mean species richness of parasite infracommunities harbored per host in cultured fishes was significantly higher (2.13) when compared with that in wild ones (1.87). T. zillii infracommunities are dominated by monogenean species. The diversity (Brillouin index) of parasite community in wild fishes was 2.05 while in cultured fish was 2.08. The value of Berger-Parker in wild fish was 0.41 and 0.28 in cultured fish. Host sex, host size (length) and fish origin (wild or cultured) played significant role in determining infracommunities species richness. Infracommunities species richness of T. zillii was positively correlated with body size.