The present study was carried out to investigate the effect of malachite green dye used , in dyeing and aquaculture, on the fresh water bivalve Lamellidens marginalis. The effects of sub lethal exposure i.e. 1/10th and 1/20th concentration of LC50, were studied by changes in the bichemical constitutes like total glycogen, protein and lipid in different tissues like gill, hepatopancreas, gonad and mantle for 30 days exposure period. The glycogen content in selected tissues showed significant depletion (p<0.001) at both the concentration. The mantle showed maximum significant depletion in protein content at both i.e. 1/20th and 1/10th the concentration, (-28.77%) and (-37.77%) respectively compared to other tissues. The lipid showed significant decrease in gill (-21.31%) and mantle (- 46.31%) at the 1/20th and 1/10th concentration
