Electron microscopic study on selected fungal infected organs of rainbow trout and Indian hill trout scanning from central Himalaya

In the present study, fungal infected and healthy adult rainbow trout (Oncorhynchus mykiss) and Indian hill trout (Barilius bendelisis) were examined under scanning electron microscope to investigate the pathological alterations in gill, fin, skin and eye. The gill lamellae of infected rainbow trout were found ruptured and showed structural disorganization with fusion of respiratory lamellae and reduced interlamellar space. The eyes were found to be completely covered with mycelium. Descaling, scale erosion, abrasion of the skin and sloughing off epithelium was noticed in infected fish. The fins were found to be invaded by fungal hyphae and mycelium covered the fin epidermis. Moreover, the epithelial structure of fins was lost. In conclusion, fungi primarily infected all the boundary tissues which resulted in pathological alterations and eventual mortalities.