IMPACT OF INDUSTRIAL EFFLUENT ON THE CHANGES IN BEHAVIOUR AND BODY WEIGHT OF A FRESH WATER FISH, Oreochromis mossambicus, Peters

Zoology

One must continue to anticipate increasing density of urban population with all the problems of air, water pollution and waste disposal. The most important thing is the introduction of chemical substances into the environment, which never before existed in nature. Emissions of effluent from various industries into water bodies are having detrimental effects on aquatic species like fish. High percentage of mortality of fish due to the action of the effluent might be due to the pathological changes. The present investigation was designed to study the effect of effluent of a chlor-alkali industry on behaviour & body weight of a fresh water fish, Oreochromis mossambicus, Peters and its toxicological significance. The MAC value of the effluent was found to be 6.41 ml/l for 30 days and to be on the safer side 6.0 ml/l was considered for 28 days of the exposure for sub-lethal toxicological studies. The LC10, LC50, LC100 values after 28 days were recorded. It has been observed that all the exposed fishes appeared lethargic after exposure to the effluent. The major clinical symptoms such as inappetance and ataxia appeared immediately after exposure. At higher concentration, the exposed fish showed loss of equilibrium, gradual onset of inactivity, erratic swimming with irregular collision to the inner glass wall of the aquarium were observed. Infection of eyes, exophthalmia and involusions of test fish were observed, when compared to control fish. The body weight showed a linear increase showing the existence of significant positive correlation with the exposure period in the control set. Body weight of the control fish increased by 1.26 % on 7th day of exposure, by 3.65 % on 14th day of exposure. On 21st day of exposure 7.24 % increase in body weight was marked. On 28th day of exposure, 9.25 % increase was recorded. Whereas, a significant negative correlation was observed between the exposure period and body weight. With the increase in exposure period, the body weight significantly declined. The body weight of the exposed fish gradually decreased during the exposure period and On 7th day of exposure 7.2 % decrease, on 14th day of exposure, 14.96 % decrease, on 21st day of exposure 25.06 % decrease, on 28th day of exposure, 31.89 % decrease was recorded, when compared to its respective control values. Control fish did not show any signs of toxicity. No recovery in body weight was marked, when the exposed fish was transferred to effluent free normal medium for recovery studies, instead of showing any recovery, 47.96 % decrease was recorded on 28th day of recovery. .

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