The research was accomplished to determinate sub lethal concentration (LC₅₀96h) of Nikel and Iron on Rutils frisii kutum. The study was performed by Water Static Method during 96 hours. The experiments were done by 13 fish with avrage weight 1±0.5 g. The fish were encountered with different concentrations of Ni (5, 15, 25, 30, 35, 40 mg/l) and Iron (100, 120, 140, 150, 155, 160 mg/l) respectively. Sulphate Nikel salt and Iron Sulphate salt were used as source of Nikel ion and Iron respectively. A group of fish was considered as control. Tempereature and pH were stable in experiments.  Under stable condition and aeration, the lethal concentration of Nickle  and Iron were detected  equivalent 40 mg/l and 155 mg/l respectively. Sub lethal concentration of Nickle and Iron were  19.35 mg/l and 124.52 mg/l respectively by used of linear regression of mortality percentage to ammonia different concentrations. Results indicate significant differences between treatments with each other (p<0.05). However,  in the high concentrations of Nikel and Iron nominal signs of toxicity as convulsion and opened operculum were observed. In microscopic tissue studies of gills showed hyperemia, hemorrhagi cell necrosis and influx of inflammatory cells.