Histopathological changes in the skins and gills of some marine fishes due to parasitic isopod infestation

Abstract

Objective: To study the histopathological symptoms owing to cymothoid isopod that were categorised as gross lesions. Methods: Nature of damage fish tissues and gills were taken from the parasite attachment area of infested and uninfested fishes which were cut out in fresh condition fixed in 10% buffered neutral formalin. Fresh and recently preserved tissues and gills were washed in tap water and dehydrated using alcohol series. The tissues gills were then cleaned in methylbenzoate and benzene and embedded in paraffin wax. The serial sections cutting 4 to 5 m thickness, were stained with Erlich’s haematoxylin and Eosin for histopathological analysis. Results: In normal muscle tissue, the tensile strength of muscle fibers with extra cellular matrix collagen was extensively tight associated. This gave a rigid musculature pattern to the tissues. Infested fish exhibited histopathological anomalies such as tissue reactions, primarily associated with the formation of granulomas consisted of macrophages and epitheleioid cells, which were occasionally surrounded by a thin rim of fibroblasts. The infestations such as lipofibrosis, hyperaemia, haemorhagic lesions and penetration of dactylus usually pressure atrophy often accompanied by the presence of parasites. Lesions had well developed granulomas that underlined in the muscle or overlying subcutaneous tissue, form these spread to underlying organs. Conclusions: It could be concluded that the infection studies of parasite that attaches or settles on the host body, at first, causes localized inflammatory changes, but with time, assuring a different or diffused character. The changes always begin with hyperaemia in the angles between adjacent sides at the site of attachment and then move towards deeply situated area.