© 2021 IJRAR October 2021, Volume 8, Issue 4 www.ijrar.org (E-ISSN 2348-1269, P- ISSN 2349-5138) IJRAR21D1132 International Journal of Research and Analytical Reviews (IJRAR) www.ijrar.org 199 Lead Nitrate Induced Histopathological Alterations in Gills of Clarias gariepinus Ranjeeta Chatterjee and Abdulkarim Shaikh* Department of Zoology, Prof. Ramkrishna More ACS College, Akurdi, Pune Maharashtra, India – 411044. Abstract: The heavy metals which are essential for normal life processes become toxic to the aquatic organisms when released continuously into the water bodies. They exert synergistic and antagonistic effects on each other which change the water quality and thereby affect the primary producers of aquatic communities. Heavy metals by direct contact with microorganisms and fish, enter into human population and accumulate producing deleterious effects. Toxic levels of heavy metals not only change the physico-chemical properties of water, but also cause various severe pathological lesions in the structure and functions of cells including enzymatic and metabolic pathways of both flora and fauna. In the present study, effect of sublethal concentration of lead nitrate on the gills of Clarias gariepinus was studied. The result indicates that Lead nitrate is toxic to the fish. The changes include fusion of secondary lamellae, haemorrhage, oedema, necrosis and other degenerative changes. Keywords: Lead nitrate, Clarias gariepinus, gill lamellae, gill filament, histopathology, hypertrophy, hyperplasia. I. INTRODUCTION Ever since man embarked on the path of civilization, he began to exploit and pollute air, water and land indiscriminately without realizing or caring for the long range and long term effects of his action in the form of environmental pollution. This has resulted in imbalance of the ecosystem, which has now reached a state of environmental crisis (Gimeno et al., 1995). The aquatic environments covered about 71% of the earth surface and in this environment about 28,000 fish species inhabited along with other innumerable aquatic organisms. Heavy metal in water quality and their effect on aquatic environmental have received much attention. Metals like Cu, Cd, Zn frequently found in natural water in parts per billion. In trace quantity heavy metal serve as essential micronutrient for enzymatic transformation. Anthropogenic activities have resulted in an increase in pollution of many heavy metals. The metals are of special concern, because of their diversified effect and the range of concentration stimulated toxic ill effect to the aquatic life forms (Coombs, 1980). Lead(II) nitrate is an inorganic compound with the chemical formula Pb(NO 3 ) 2 . It commonly occurs as a colourless crystal or white powder and unlike most other lead(II) salts, is soluble in water. Lead(II) nitrate does not occur naturally. Lead and lead compounds are generally toxic pollutants. Lead(II)salts and organic lead compounds are most harmful ecotoxicologically. Lead salts are attributed to water hazard class II, and consequently are harmful. Through plant uptake, lead enters food chains. Consequently, lead based pesticide application is prohibited in most countries. Lead accumulates in organisms, sediments and sludge. Lead in wastewater mostly stems from streets and roofs. Lead exists as four stable isotopes, and no less than 26 instable isotopes (Christensen et.al. 1977). The micro and macro fauna in aquatic environment are hence in threat of lead pollution. As fish is the major diverse group of animals that live and breathe in water, hence are best model to study pollution index. The increased levels of Pb in the water can increase mortality rate and may cause many biochemical and histopathological alterations in survived fish. Studies of histopathology have been recognized to be reliable bio-indicators of compression in fish. The histological changes on fish is a noteworthy and promising field to understand the extent to which changes in the structural organization are occurring in the organs due to environmental pollution (Moitra et al. 2012). Singh et al (1990) studied environmental pollution and its effects on aquatic animals. Heavy metal toxicant leads to many pathological changes in different tissues of fish and has been reported for Labeo rohita exposed to mercuric chloride and Chana punctatus exposed to phenyl mercuric acetase (Karuppasamy, 2000). Srivastava et al. (1982) have observed the hisotopathological changes and accumulation potential in the fish tissues under chromium stress. The liver tissues of Heteropneustes fossils exposed to a sublethal concentration of malathion showed hypertrophy of hepatic cells and liver cord disarray, vacuolation of cytoplasm and necrosis, rupture of hepatic cell membrane and necrotic centrolobular area (Dutta et.al., 1993). L. rohita showed histological changes due to aflatoxin given to fish intraperitoneally (Sahoo et al., 2001). The fish are aquatic and breathe through gills. The gills are hence the primary initial target of toxicity as it is exposed at the most to the toxic environment, i.e. water. The cytological changes in gill morphology in fish usually occur as a result of contaminant exposure. Hence, gills were selected to study the histopathological alterations.