The present study was to investigate the effect of dietary protein levels on growth, feed utilization and nitrogen metabolism of grass carp(Ctenopharyngodon idellus). Five isoenergetic diets(13.71 kJ/g) were formulated with 15%, 20%, 25%, 30% and 35% protein level. Fish(209 ± 10 g) were randomly distributed into five groups each with three replicates and were fed twice daily(08:00 and 16:00) to apparent satiation for 8 weeks. The results showed that weight gain and feed utilization were significantly affect...