Parasite community of wild and cultured oreochromis niloticus from lake Manzalah, Egypt

A total of 323 O. niloticus [168 wild fishes and 155 cultured fishes] were collected from Lake Manzala, Egypt from July to September 2010. The fish samples were examined for both ectoparasites and endoparasites. The parasite community of wild and cultured, O. niloticus consisted of ten parasitic species, one protozoon [Trichodina spp.], six monogenea [Cichlidogyrus sclerosus, C. thurstonae, C. hallitypicus, C. tilapiae, C. ergensi, C. tiberianus], one acanthocephalan [Acanthogyrus [Acanthosentis] tilapiae] and two crustacean species [Lernaea cyprinacea and Ergasilus sp.]. Mean parasite species richness significantly differed between wild [4.9 +/- 0.3] and cultured [6.6 +/- 0.8]. The overall prevalence of infection in cultured O. niloticus [54.84%] was significantly higher as compared to that in wild fish [39.9%]. The most prevalent parasite was C. thurstonae [37.46%] and C. sclerosus [35.91%] while the less prevalent one was Ergasilus sp. [14.55%]. Host sex and host body size significantly affect parasitism in most parasite species

Microhabitat and surface ultrastructure of neothoracocotyle commersoni and pricea multae [monogenea: microcotyloidea] from gills of scombrid fish, scomberomorus commerson

The microhabitat and surface topography of microcotylid monogenean parasites Neothoracocotyle commersoni and Pricea multae from gills of Spanish mackerels, Scomberomorus commerson, was investigated. The results showed that N. commersoni was aggregated at the first gill sector, while P. Multae was aggregated at both first and second sectors in single infestation. On contrary, in mixed infestation, N. commersoni occupied the first sector of gills and P. Multae was restricted only at the fourth sector with a high intensity of infestation compared with N. commersoni. The aggregation of single species of monogenea in restricted habitat may aid in the cross- fertilization, hence produce hybrids strains of parasites which might be more potent and vicious causing severe damage to the host. The surface ultrastructure of the representative monogenea showed that the tegument was provided with microvillus-like projections that suggested metabolic exchange and absorption of micromolecular nutrients from the surrounding environment. The architecture of clamps of N. Commersoni differed from that of P. Multae in possessing microvillous-like projections, which may act as an organ of nutrition, beside its principle attachment function. The ultrastructure of the clamps of both species provided an aid in understanding of the parasite habitat and survival