Pollution is the negative feedback of the environment which affects living organisms. In recent times interest has been focused on rivers and estuaries as these are considered major sources of pollutants of aquatic medium. Human beings have been responsible for marine pollution, as they have introduced directly or indirectly, harmful waste substances into the marine environment. Estuaries and rivers have not been spared with the result the deleterious effects have paved the way for health hazards to human beings. Fish are one of the most widely distributed organisms in the aquatic environment and, being susceptible to metal contamination, may reflect the extent of the biological effects of metal pollution in waters. The effect of mercury chloride on protein and amino acid contents of brain and muscle of freshwater fish, Hypophthalmichthys molitrix has been studied. The fish were exposed to sublethal concentrations of mercury chloride 1/5th (high), 1/10th (medium) and 1/15th (low) of the 96-hour LC50 for the period of 10, 20 and 30 days. All the sublethal concentrations of mercury chloride exposed fish for the period of 10. 20 and 30 days showed decrease the protein and increase the amino acid content in brain and muscle of Hypophthalmichthys molitrix. The significant alterations showed toxic effect of heavy metal mercury chloride at biochemical levels.
M. Muthulingam (Tue,) studied this question.