Compared with the control, the activity of superoxide dismutase increased in chromium treated fishes during 24 to 72???hrs and decreased in 96???hrs in all the tissues except in brain where the activity of SOD was higher than normal even after 96???hrs of treatment period.Figure 4: (a)???(d) Effect of hexavalent chromium on superoxide dismutase activity in liver (a), muscle (b), gills (c), and bra