Impact of fluoride on structural changes in gills of indian catfish, Heteropneustes fossilis (Bloch.) after acute exposure

Present study reveals toxicopathological impact of fluoride on fish gills. Freshwater catfish, Heteropneustes fossilis subjected to acute exposure of fluoride showed severe histopathological alterations in gills after 24, 48, 72 and 96 hours. Major alterations during initial stage include necrosis, inflammation, swelling in primary and secondary gill lamellae, degeneration, cuticular eruption and reduction in interlamellar spaces; whereas clubbing of gill tips, hyperplasia, nuclear pyknosis, fusion of gill lamellae, hypertrophy of epithelial cells and broken tissue debris near gill base were observed during late hours. Ultimately these lytic changes produced complete disorganization of gill structure. The severity of alterations was found duration dependent. Thus it is clear that fluoride alters the normal histoarchitecture of gills and higher concentration can result into large scale fish mortality due to asphyxiation.