Water pollution with chromium (Cr⁺²) is a major threat to the environment and human health. Therefore this study was conducted to evaluate the efficiency of aquatic plant Lemna minor as a natural biological tool in the accumulation of Cr⁺² from polluted water under the effect of pH and Ethylene Diamine Tetra Acetic Acid (EDTA) and assess the impact of this treatment on the growth of  Nile tilapia. L. minor fronds were exposed to different concentrations of Cr⁺² (0, 2, 4, 6, 8 and 10 mg L^-1) with pH (5, 6, 7, 8 and 9) for periods of 5, 10, 15 and 20 days. The highest accumulation of Cr⁺² was (9563.81±222.47 μg g^-1 dry wt) at 10 mg L^-1 with pH 5 after 10 days of treatment. While in the groups that enriched with EDTA (25, 50, 75 and 100 μM) for periods of 5, 10, 15 and 20 days, maximum accumulation of Cr⁺² was (9926±235.84 μg g^-1 dry wt) at 10 mg L^-1 with pH 5 and 25 μM of EDTA after 10 days of treatment. The highest removal efficiency of Cr⁺² by L. minor was 99.26 % at 10 mg L^-1 with pH 5 and 25 μM of EDTA after 10 days of treatment. This study indicated that pH and EDTA influenced chromium accumulation in L. minor. The impact of the treated water by L. minor on the growth of Nile tilapia indicated that fish muscles had no chromium accumulation and the treated water became acceptable and safe. Meanwhile; a specific growth rate (SGR) was (1.2±0.01 %/day) at the end of exposure period which lasted 30 days the same as control group. So, we can conclude that Nile tilapia played an important role in monitoring chromium in the treated water by L. minor under the effect of pH and EDTA.