UTTAR PRADESH JOURNAL OF ZOOLOGY

Discharge of industrial, municipal and agricultural wastewater into freshwater ecosystems introduces pollutants such as heavy metals, nutrients and organic loads that can affect aquatic organisms. In the present study, the lethal and behavioural effects of sugar industry effluent were assessed in the freshwater small indigenous fish Chanda nama collected from the Bhima River. Effluent was collected from the canal confluence at Patas village, and test fish were acclimatised under laboratory conditions before exposure. Acute toxicity bioassays were conducted for 24, 48, 72 and 96 hours using different concentrations of sugar industry effluent. The estimated LC50 values declined with increasing exposure duration, from 15.5% at 24 hours to 15.0%, 14.5% and 14.0% at 48, 72 and 96 hours, respectively. Fish exposed to lethal concentrations exhibited clear behavioural changes, including increased opercular movement, jerky and erratic swimming, excitation, loss of equilibrium, attempts to escape from the aquarium, leaping out of water and repeated contact with the aquarium wall. Mortality increased with concentration and exposure duration, indicating a time-dependent toxic response under laboratory conditions. The findings suggest that untreated or inadequately treated sugar industry effluent may cause acute stress and mortality in freshwater fish. Proper effluent treatment, routine monitoring and further chemical characterisation are needed to better understand the toxic components and reduce potential ecological risks.