Assessment of aluminium chloride (AlCl<sub>3</sub>) toxicity in histological changes in the kidney of <i>Cirrhinus mrigala</i>

Water is indispensable for sustaining life. The present study aimed to find out the lethal concentration (LC50) of aluminium chloride (AlCl3) and its histological alterations in the kidney of freshwater fish Cirrhinus mrigala. A study was based on an experiment design based on lethal concentration. The LC50 of aluminium chloride in fish was reported to be 0.087ml/L after 24, 48, 72 and 96 hours. To do further evaluation, the fish were exposed to AlCl3 sublethal concentration 1/10th of LC50, i.e., 0.0087ml/L, for 7, 14, 21 and 28 days. After exposure to aluminium chloride, changes in behaviour, including erratic swimming, heightened sensitivity to stimuli, irregular fin movements, congregating at the tank, loss of balance, aggressiveness and respiratory distress, were noticed in C. mrigala. The kidneys of control fish showed no significant changes, while in the treated group, morphological changes were observed in each experimental duration, including a decrease in the number and size of tubular cells, expansion of tubular lumen, degeneration and damage in epithelial cells, necrosis, expanded Bowman’s space, blood cell around tubular and interstitial cells and glomerulus enlargement were observed in kidney tissues. This histological analysis showed that the degree of alterations in fish kidneys increased time-dependent. These histological changes are early warning signs of environmental health risks, showing that even low levels of heavy metal contamination can severely impact aquatic life and the entire food chain, with direct and indirect consequences for human lives and nature.