Effect of different feeding regimens on physiological indicators, intestinal transcriptome, and bacterial flora of mandarin fish (Siniperca chuatsi).

Mandarin fish (Siniperca chuatsi) represents a typical carnivorous freshwater economic fish in China. Recently, the study of their feeding behavior to acclimate formulated diets has become a research focus. This study evaluated the effects of various diets on the body composition, nutritional content, digestive enzyme activity, gene expression, and gut microbiota of mandarin fish. Firstly, no significant differences were found in the muscle's basic nutritional components (moisture, crude protein, crude fat, and crude ash), as well as in the fatty acid and amino acid content, between the live feed group (LFSC) and the compound feed group (CFSC). However, mandarin fish in the LFSC group exhibited significantly higher lipase activity in the liver and intestine compared to the CFSC group, while amylase activity in the intestine showed an opposite pattern. Additionally, intestinal transcriptome analysis revealed 6238 differentially expressed genes and identified several differentially expressed clock genes associated with diet type. Furthermore, gut microbiota analysis indicated that different feeding regimens influenced microbial composition, revealing correlations between bacterial genera and intestinal gene expression levels. These findings provided novel insights into the gut microbiota and transcriptomic responses of mandarin fish to different dietary types.