In recent decades, pollution of freshwater and riverine ecosystems is indorsed to heavy metals contamination. Among various causes, heavy metals are the most concern. Many aquatic organisms have the ability to inhabit in contaminated environments, due to their defense mechanisms that allow detoxification, excretion, anti-oxidant protection and stress response. Lamellidens marginalis have the potential to accumulate the heavy metals. In the present study, the mussels were exposed to 1, 5, 10 and 15 ppm concentration of mercuric chloride for 96 hrs. Enzymatic and antioxidant parameters including catalase (CAT), superoxide dismutase (SOD), lactate dehydrogenase (LDH), hydrogen peroxide (HP) and lipid peroxidation (LPO) levels were used as effective criteria. All the parameters showed responses in gills, abductor muscle, mantle tissue, gills and gonads with exposure to HgCl 2 . Collectively, these parameters could be used as biomarker for heavy metals contamination in aquatic system using L. marginalis.