An attempt was conducted to save water in fish aquaculture[he1]  by replacing the water exchange cycle in aquaculture with water acidification. Thus a study was organized to reduce the toxic effect of harmful substances, especially ammonia on Oreochromis niloticus fingerlings in farming water and maintain the water quality. In addition, this work aimed to assess the effectiveness of different acids in removing ammonia and detect the tolerance of the Nile tilapia to different low pH and acidified water by evaluating its survival and growth performance. The survival rate of the Nile tilapia fingerlings [he2] was 0 %, 0 %, 30 % and 80 % at pH of 3, 4, 5 and 6 in water acidified using hydrochloric acid (HCL); while, in water acidified with acetic acid (Ch₃COOH) it was 0 %, 0 %, 80 % and 90 % at pH 3, 4, 5 and 6. The control aquarium water and the aquaria treated with Ch₃COOH at different pH levels had significantly similar concentrations of ammonia (NH₃), nitrite (NO₂) and nitrate (NO₃). Initial body weight (IBW), final body weight (FBW), weight gain (WG), specific growth rate (SGR) and the survival (%) of Nile tilapia in control group and groups exposed to different concentrations of ammonium chlorides (NH₄CL) and treated with CH₃COOH at different pH levels showed a significant difference increase compared to the fingerlings exposed only to different concentrations of NH₄CL. The data clearly demonstrate that the water acidification with Ch₃COOH was the best and cheapest for fish survival and growth, as well as improving water quality.  [he1]Fish aquaculture  [he2]يجب توضيح normal PH for nile tilapia