Pollution is an undesirable change in surrounding environment which affects human life in many ways. We tried to control these factors to improve our living quality. However, many times, the pollution is due to such reasons which cannot be avoidable like daily need product preparation plants. Sugar is a part of our life now. Sugar mills produce large quantities of undesirable byproducts which pollute our surroundings. Finally, these pollutants go to water bodies and pose effect on aquatic organisms. Keeping these points in view, the effect of sugar mill effluent is observed on gill histology of freshwater fish Channa punctatus