The present study deals with the effect of different concentrations of EDTA (0, 0.1 & 0.3 g EDTA /L) on the growth in length, weight, survival rate, growth performance and physiological characters of the Nile tilapia, Oreochromis niloticus
fingerlings reared in glass aquaria. The improvement of fish fingerlings development obtained by EDTA is dose-dependent. Fingerlings obtained from high concentration of EDTA (0.3 g EDTA /L) showed higher increase in length, weight and survival rate than those of low concentration (0.1 g EDTA /L) and control. The total weight gain,
average daily gain and specific growth rate of O. niloticus, fingerlings improved with the high concentration of EDTA compared with the low concentration and control. The best feed conversion ratio (1.82) was recorded in the fish fingerlings exposed to 0.3 g EDTA/L compared with the control (2.1) and fingerlings exposed to 0.1 g
EDTA/L (2.44). Biochemical analysis indicated that, EDTA in high concentrations are useful additives for isolated or/ and reducing dangerous substances from different fish tissues and surrounding media, thus improved the physiological responses.