phytofilteration using aquatic plants has promising potential for exist clean up of polluted water .Hence,Spirolina platensis may have apotential to be used as a natural feed supplement for protecting fish against heavy metals toxicity .This study investigate the effect of sodium sulphate on O. niloticus and the amelioration effects of spirolina platensis on its adverse effects , determination of 96hrs.LC50 ,chronic toxicity by exposed of oreochromis niloticus to 1/10 dose of sodium sulphate 96hr-Lc50 (5.8mg/L) and study the changes in serum biomarkers of liver and kidney function ,total antioxidants capacity (TAC) and lipid perioxidation (LPO). Two hundered and sixty of nile tilapia were used for determination of LC50 and chronic toxicity of sodium sulphate . the fish were allocated to four groups of 50 fish each control group received no any treatment , sodium sulphate (5.8mg/L), sodium sulphate (5.8mg/L) plus spirolina platensis extract spirolina platensis 1% of diet . the results showed that sodium sulphate at dose 5.8mg/L the level of serum total protein, albumin, globuline and TAC in serum of nile tilapia are significantly decreased. The ALT, AST activity and LPO contents of sodium sulphate exposed group was found higher than the spirolina platensis supplemented groups. On the basis of present findings it could be concluded that increase sodium sulphate in water cause adverse effect on fish blood biochemistry,the changes of serum biomarkers were the physiological responses of oreochromis niloticus to the stress of sodium sulphate exposure.spirolina platensis can be grown to produce natural products against heavy metals toxicity