Negative impacts of implantation of myxozoan’s cysts in tissues of Labeo senegalensis (Cyprinidae) and Oreochromis niloticus (Cichlidae) in Maga Lake (Maroua, Cameroun).

Labeo sanagalensis Boulenger, 1902 and Oreochromis niloticus Linneaus, 1758 are freshwater fish species with high nutritional, aquaculture and commercial value (Montchowuie et al., 2010; FAO, 2017). These species of fish, cultivated in Lake Maga, are infected by four species of myxozoans. Species of Myxozoans are known to induce several damages on fish tissues in wild and cultured stocks throughout the world (Lom & Dykovà, 2006). So, to fully understand the impact of the implantation of these parasites in the tissue of L. senegalensis and O. niloticus in lake Maga, we undertook a histological study of the muscle, the gill, the eyes and ovaries infected by Myxobolus fomenai Abdel-Ghaffar, ElToukhy, Al-Quraishy, AlRasheid, Abdel-Baki, Hegazy & Bashtar, 2008, M. nchoutnouensis Nchoutpouen & Fomena, 2011, M. djafgai and M. kainjiae Obiekezie & Okaeme, 1990 respectively. Classical methods concerning fish dissection, identification and description of parasites under the light microscope as well as established histopathologic techniques were used. Histological analysis revealed that: In L. senagalensis the cyst of Myxobolus fomenai, located between muscular fibers cause myolysis of adjacent fibers; obstruction of the artery, local swelling of the branchial filament and stagnation of blood cells were the consequences of the implantation of M. nchoutnouensis cysts in the gills; In O. niloticus sections, swelling of the sclera and monocytes were observed around the cyst of M. djafgai. In the ovaries of this cichlid fish, M. kainjiae’s spores occupy and destroy the vitellus of mature oocytes. Follicle expansion and burst were the final stages after the complete invasion by the spores. All observations made revealed that cyst implantation of myxozoan have negative consequences on their hosts. Furthermore, in case of higher infection, flesh quality may be altered; respiratory and reproductive functions can be compromised.

Keys words: Histopathology, fish, Myxozoan, parasite, damage, Lake Maga.