A study with increasing levels of a plant protein mixture(PM) replacing fish meal (FM) in diets for juvenile Nile tilapia,was conducted to elucidate effects on its growth performance,body conposition and digestibility.The PM was consisted of 25% cottonseed meal,25% rapeseed meal,25% corn gulten meal and 25% broad bean.Five isonitrogenous (crude protein 30%) and isoenergetic (20 kJ/g) diets replacing 0%(control),25%(PM25),50%(PM50),75%(PM75) and 100%(PM100) of the FM with PM were formulated.Each experimental diet was fed to triplicate groups with 30 Nile tilapia juveniles (initial body weight 7.16±0.81 g) in 400 L aquaria for 10 weeks.The water temperature was 21±0.5℃,and dissolved oxygen was approximately 5.0 mg/L during the experimental period.The results showed that weight gain rate(WGR),specific growth rate(SGR),feed conversion ratio(FCR) and protein efficiency ratio(PER) of fish fed with diets PM25,PM50,PM75 were not significantly different from those of fish fed with control diet,while fish fed with PM100 had significant difference with those of fish fed with the other diets.No significant differences in HSI and VSI were observed among dietary treaments.The whole body proximate analysis showed that protein and ash contents significantly decreased with increasing dietary PM levels,while the whole body lipid content increased.Except hisidine content was increased with increasing dietary PM levels,there were no significant effects on muscle indispensable amino acid (IAA) and total amino acid contents.Taste amino acid to total amino acid ratio decreased with increasing dietary PM levels,and no effect on total amino acid content was observed.PM substitution up to 75% of the FM protein did not result in differences in the apparent digestibility of protein and total amino acid compared with the control,whereas in the PM100 group digestibility was significantly lower than the other groups; no significant effects were found on lipid digestibility.These results suggest that 75% FM replacement by PM caused no significant effect on the growth,body composition and digestibility of Nile tilapia.