Kritika Pandey*, Farha Ashique, Dileep Kumar & Parimal Kumar Khan
Department of Zoology, Patna University, Patna, Bihar, India
Received : 08th May, 2024 ; Revised : 05th June, 2024
DOI:- https://doi.org/10.5281/zenodo.14991623
Abstract– Zinc is an essential heavy metal that plays a crucial role in various biological processes. Its excessive presence in aquatic system, however, possess substantial risks to aquatic life. This study aimed to determine the acute toxicity of zinc sulphate (ZnSO4) in terms of median lethal concentrations (LC50), as well as morphological and behavioural changes in the catfish Clarias batrachus upon its short-term exposure. Physico-chemical parameters of the water, such as pH, temperature, dissolved oxygen, total hardness, and total alkalinity, were consistently monitored and maintained within optimal ranges which include 176±3 mg/l CaCO3 hardness and pH 7.0±0.5. The results revealed a dose-dependent increase in mortality rates as well as marked behavioural and morphological changes. The LC50 value of zinc sulphate was determined as 170 mg/l through probit analysis. Severely altered morphological and behavioural patterns were observed upon exposure to zinc at its acute levels. Behavioural responses included loss of equilibrium, hyperactivity, loss of reflexes, gasping at the surface, increased mucus secretion, and morphological effects were discoloration, swollen abdomen, posturing of pectoral fins and occasional haemorrhaging. Symptoms were more prominent when fish were exposed to higher levels of zinc sulphate, indicating induction of physiological stress upon exposure to excessive zinc. The observations highlighted the ecological risks posed by zinc contamination in aquatic systems signifying the need of developing effective environmental protection strategies.
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