Proximate composition is one of the most significant aspect in fish nutrition. The effect of parasitic isopod on edible fishes showed a significant decrease in proximate composition and considerable histopathological alterations. Among the parasitized fish species, the maximum protein content was found in Parastromateus niger (18±0.96 µg/g). Whereas, the carbohydrate level was found maximum in Arius maculatus (0.9±0.32µg/g) and minimum in Thryssa mystax (0.3±0.28µg/g). In case of lipids, maximum value was found in Rastrelliger kanagurta (0.9±0.2µg/g) and minimum in Trichiurus lepturus (0.2±0.1µg/g). The present findings demonstrate the variations in the proximate composition of parasitized and unparasitized fishes. Histopathological observations on the parasitized host displayed several changes on the morphology of the muscle tissue and gill lamellae. The investigation revealed that parasitic isopods have ability to affect the health of edible fish species.