Effects of dietary arginine levels and carbohydrate-to-lipid ratios on mRNA expression of growth-related hormones in largemouth bass, Micropterus salmoides

► A nutrition-endocrinological study in largemouth bass was conducted for the first time. ► Dietary Arg levels differentially regulated GH, IGF-I and insulin at transcription level in the source tissues. ► Dietary carbohydrate-to-lipid ratios regulated GH, IGF-I and insulin expression in a ratio-specific manner. ► Hepatic IGF-I mRNA level could be used as an index of growth performance and nutritional fitness.