------------------------------------------------------------------------------------------------------------------------------------------------------This study was carried out to assess the proximate composition of Tilapia (Oreochromis niloticus) and Mackerel (Scomber scombrus) treated with varying concentration (1%, 3% and5%) of sodium metabisulphite, sodium benzoate and potassium sorbate during 8-week storage at refrigeration temperature. Biochemical study showed a slight decrease in protein and lipid content while the moisture content and pH increased. This study shows that Potassium sorbate is more effective in preservation of the fishes than Sodium benzoate and Sodium metabisulphite at equal concentration. Sodium metabisulphite was the least effective. The results of the whole study indicated that despite some changes in the biochemical properties during prolonged refrigeration storage at 4oC, the treated fishes appeared to be suitable for refrigeration storage and the combination of low temperature and addition of preservatives helps to slow down deterioration. -------------------------------------------------------------------------------------------------------------------------------------------------------