Pattern and potential pathophysiological effects of myxosporean infections in the gills of Tilapia species (Teleostei: Cichlidae) from BéninDownload PDF
In order to fill the gap between natural fish catches and estimated needs of populations in animal protein consumption, aquaculture required suitable fish. Indeed, much interest has focused worldwide on tilapia species. In this study, three parasites previously described, Myxobolus zillii, M. dossoui and M. beninensis were recorded on Tilapia zillii and Sarotherodon melanotheron melanotheron from Lake Nokoué (Bénin) from November 2011 to december 2012. The pathological investigation by electron microscopy revealed that the spores of M. zillii and M. dossoui were in direct contact with the cartilage of gill arch or filament but M. beninensis developed cysts within the connective tissue of gill arch. The mass of spores and continuous growth of cysts spark hollows in cartilage and connective tissues offering them the capacity to destroy these structures so that the physiological pivotal role of gill in respiratory function and ions balance might be disrupted. Among the 180 examined specimens, 27 T. zillii were infected by M. dossoui or M. zillii and 6 S. melanotheron melanotheron took in M. beninensis. No significant difference was observed within sexes and classes of length in regard to the rate of infection except the prevalence of M. dossoui which varied significantly within the seasons.
Keywords: Gill, Histopathology, Myxosporea, Prevalence, Tilapia, Lake Nokoué.