Studies on heavy metal concentrations show the magnification of discharged metals as they pass one tropic level to another. Amongst the fiddlers, Traingularis appears to pick up a higher load of metals than its relative. No significant difference has been observed between males and females. Nickel appears to be taken up by the gills, hepato pancreas and ovary. Copper gets accumulated in the hepato pancreas. Oviparous females exhibit higher concentration of zinc in the ovary