New Insights on the Effects of Monogenean Gill Parasites on Naturally Infested Scoberomorus commerson: Host Response, Electron Microscopy, and Histopathological Studies

Fish are frequently regarded as the most significant source of income due to their high economic value. The infection of monogeneans is the main cause of fish anemia leading to high mortalities. Thus, this study aimed to detect monogeneans parasites in Scoberomorus commerson and investigate the histopathological changes related to its natural infections. Furthermore, to research the potential parasite-host interactions. One hundred marine fishes ( S. commerson ) from the Ezbet-El Borg area, Damietta province, Egypt were examined from August 2022 to January 2023 for the presence of monogenean gill parasites. 38 fish were infected with monogenean species: Pricea multae 32% and Gotocotyla acanthura 19%. The structure of P. multae and G. acanthura were explained by using light and scanning electron microscope (SEM), the infected fish have no pathognomonic lesions, but for a few cases showed excessive mucus secretion. The pathological and ultrastructural results revealed massive branchial damage with partial to complete lamellar fusion and lamellar desquamation with complete loss of secondary lamellae and lymphocytic infiltration, the host response includes the appearance of numerous ruffled lymphocytes and mucous globules at the site of parasitic attachment.