Growth performance and feed utilization results are shown in Table 3. Fish fed ≥2.22% arginine exhibited significantly (P b 0.05) higher growth performance than those fed 1.42% arginine. Slight improvements in feed conversion ratio (FCR) and protein efficiency ratio (PER) were obtained by increment of dietary arginine level but the differences were not significant among the treatments. However, fish fed 2.54% arginine showed significantly higher protein productive value