The main objective of this study was to evaluate the effect of partial and total(0%, 25%, 50%, 75%, and 100%) replacement of soy bean meal (SBM) protein by guar  meal (Cyamopsis tetragonoloba ) (GM) protein in commercial diets on water quality, ,survival rate %, growth performance, feed utilization , whole body composition , physiological parameters and  economic efficiency of Nile tilapia, Oreochromis niloticus fry. Fish fry with an average initial weight of 0.825± 0.01 g/fish were stocked at a rate of 10 fish/aquarium (100L water) for 84 days experimental period. Five experimental diets were formulated to be isocaloric (454.34 kcal GEl/100 g dry matter, DM) and isonitrogenous (30.25% crude protein, CP %). The results of this study revealed that, the highest (P≤0.01) final weights, specific growth rate, protein and nutrient utilization were recorded by GM 25 and 50% groups followed by the control group and the GM 75 and100% groups, respectively. Therefore, these results suggest that the replacement of 25 and 50% of SBM by GM had a significant increase on fish growth performance (final body weight, average body weight and Specific growth rate %) , feed and nutrient utilization respectively , however replacing of the higher GM levels (75 or 100%) significantly (P≤0.01) reduced them . The group fed on 50% GM exhibited comparable growth performance to those fed SBM based diet. Carcass CP% was significantly (P ≤ 0.01) increased with the increase of dietary GM up to 50% and decreased with 75% and 100% levels. Dietary GM levels does not show any significant effects on carcass ether extract (EE %). Increasing GM up to100% increased carcass ash content significantly (P ≤ 0.01) while energy content (EC) values were decreased. Hematocrit and hemoglobin values (hematological parameters) were almost decreased proportionally with increasing the dietary GM with the largest declines in groups fed on 75-100% GM levels. Values of serum transaminases (aspartate aminotransferase, AST and alanine aminotransferase, ALT) were almost increased with the increase in GM level as a substitute for SBM in Nile tilapia diets. Therefore, these results suggest that up to 50 % of soy bean meal protein can be replaced by guar meal protein in mono sex Nile tilapia diets without any adverse effect on growth performance and feed utilization.