Histopathological study of parasitic effect of Dactylogyrus vastator (Nybelin, 1924) on the Catla catla in culture ponds in Darbhanga

Abstract

The current investigation was undertaken to study the gill histopathologies due to infestation of helminth parasite, monogenetic trematode, Dactylogyrus vastator (Nybelin, 1924) in the Indian major carp, Catla catla. There were only symptomatic samples of diseased fishes comprised of fingerlings and adults of Catla catla collected and examined. Behaviour respond studied- partial suffocation, lethargic swimming and clinical sign observed as their gills were very pale in colour and had haemorrhagic and inflamed areas at the sites of parasite attachments. The significant histopathological lesions and changes were seen in the gills where the parasites were found attached to the lamellar tissues causing local erosions of the epithelium and hyperplasia of the secondary lamellar epithelium and fusion of adjacent secondary lamellae, vascular congestion leading to aneurysm besides, clumbing of the tips in secondary lamellae, congested gill showed accumulation of blood leading to swelling hypertrophy in secondary lamellae, autolysis of epithelium and secondary lamellae and severe edema and necrosis were observed in gill of C. catla. No changes were noticed in other organs of the affected fishes. In severe infestations the fishes showed growth retardation. The histopathological analysis for parasites in fish will be useful tool for fish health management.