ecological studies and histopathological alterations caused by argulus japonicus among goldfish in mosul, iraq

Argulus japonicus (fish lice) is one of the the is one of the most economically significant ectoparasites infesting cultured and wild fish, predisposing hosts to secondary infections. this study aimed to investigated the ecological, epidemiological, and histopathological alterations caused by a. japonicus infestation in goldfish (carassius auratus) in mosul, iraq. a total of 320 goldfish were obtained from fish local markets and carefully examined for infestation. parasites were collected manually from the gills, fins, operculum, and skin using fine forceps, identified morphologically with standard entomological keys, and examined histologically using routine pathological procedures. of the goldfish examined (320), 197 (61.56%; 95% ci: 56.13–66.72) were infested,  yielding a total of 2,509 parasites. infestation level ranged from 1 to 25, with a mean intensity of 12.73 and abundance values of 7.84. histopathological examination revealed multiple lesions in the skin and gills of infested goldfish, including goblet cell hyperplasia, dermal edema, necrosis, hemorrhage, and gill lamellae destruction.