Figure 3: Activities of enzymatic antioxidant (A): Catalase, (B): Super Oxide Dismutase and (C): Glutathione Peroxidase in the gills, kidney and liver of C. gariepinus exposed to HgCl2 (T1=0.04 and T2=0.12 ppm) for 14 and 28 day. *Significant differences between treatments and control enzymatic antioxidant activities (p<0:05). **Significant differences between treatments and control enzymatic antioxidant activities (p<0:01). ***Significant differences between treatments and control enzymatic antioxidant activities (p<0:001).