Effect of mercury on histological alterations in gill, liver and stomach tissues of Indian catfish, Clarias batrachus

Abstract

Heavy metal pollution poses a great threat to aquatic ecosystem, ultimately threatening the survival of safe and healthy life on earth. Contaminated water persuades pathological alterations and behavioural changes in fish. Mercury is highly toxic and seriously affects aquatic organisms, ultimately affecting humans.The present study aimed to assess the histological alterations in tissues like gill, liver and stomach of Indian catfish Clarias batrachus. The fish were divided in to four groups i.e. one control (Group I) and three groups of different concentration of mercury chloride treated groups, i.e.0.0002mg/l (Group II), 0.002mg/l(Group III), and 0.02mg/l (Group IV) for 14 days. Each group contained 25 number of fish.The results indicated degenerative changes in gill, liver and stomach tissues of exposed fish. Level of changes were higher with respect to higher in concentration. Rupture of epithelial layer, club shaped gill filament, broken gill lamellae, hyperplasia of interlamellar epithelium, deletion of secondary lamellae, formation of vacuoles, blood conjugation and necrosis in gill filaments were observed in gill tissues of exposed fish. Liver damage included hepatocellular dissociation, inflamed hepatocytes, cloudy swelling, vacuole formation and hydropic degeneration. Besides, stomach tissues showed alterations such as thinner serosa, vacuolization, muscle damage, and necrosis at several points. The study confirmed that mercury is life hazardous even at very low concentration.