PATHOLOGICAL STUDIES ON EXTERNAL AND INTERNAL PARASITIC AFFECTIONS OF GOLDFISH (CARASSIUS AURATUS)

Abstract

Ornamental fish aquarium globally is considered a key sector of aquaculture and represents a significant portion of the pet industry. Between June 2022 and February 2023, a total of 229 goldfish were examined to investigate the histopathological lesions associated with the parasitic fauna (Carassius auratus) collected from Elsaieda Aisha market in Cairo governorate, Egypt and some pet shops in Beni-suef and Elfayoum governorates. The overall prevalence of parasitic infections was 47.2 %. The isolated parasites include protozoan parasites (Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. and Icthyoboda necator), monogeneans (Dactylogyrus sp. and Gyrodactylus sp.), Encysted meta cercaria of Centrocestus formosanus, crustaceans (Lernaea sp. and Argulus sp.) and one nematode Capillaria sp. with incidence rates 27.9%, 15.3%, 2.6%, 12.7% and 0.4% respectively. Gross examinations of the affected fish were varied and appeared as hemorrhage on the body' with excessive mucus production, ulceration, white-colored worm-like copepods protruding on different parts of the body and pale anemic or congested gills. Histopathological changes included vacuolation and necrosis of epidermal cells and hyperplasia and fusion of secondary gill lamellae. In addition to leucocytic cell infiltrations mainly lymphocytes and macrophages, hyperplasia of gill cartilage and parasitic cysts surrounded by several layers of fibroblast cells were noticed. In conclusion, the prevalence rate of parasite infection in goldfish is relatively high as well as the pathological findings induced by these parasites and might negatively affect the proper function of the skin and gills of the host.