Figure 2: Activities of non-enzymatic antioxidant (A): Glutathione, (B): Glutathione reductase, (C): Glutathione-S-Tranferase and (D): Total Antioxidant 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 non enzymatic antioxidant activities (p<0:05). **Significant differences between treatments and control non enzymatic antioxidant activities (p<0:01). ***Significant differences between treatments and control non enzymatic antioxidant activities (p<0:001).