Artificial Feeds Induce Hepatic Steatosis and Metabolic Reprogramming in Mandarin Fish (Siniperca chuatsi)

Artificial feeds are considered a sustainable alternative to natural live feeds for mandarin fish (Siniperca chuatsi) aquaculture, but their impacts on hepatic metabolism and growth remain unclear. In this study, a total of 800 adult mandarin fish with an initial mean body weight of 152.4 ± 8.7 g were reared for 150 days, and we compared growth performance, liver histology and liver metabolomics of fish fed artificial (AF) or natural live feeds (NF). No significant differences were observed in body length, weight, or condition factor, but the hepatosomatic index (HSI) was significantly higher in the AF group (p < 0.01), accompanied by visible hepatomegaly, pale liver color and severe hepatic steatosis. Partial least squares-discriminant analysis (PLS-DA) showed clear separation of liver metabolomes between groups. Metabolic correlation network analysis revealed tightly connected functional modules of amino acids and lipids, and key metabolites demonstrated significant group-specific changes: energy metabolism intermediates (L-alanine, α-ketoglutarate, phosphoenolpyruvate) and stress-related indicators (cortisol, γ-aminobutyric acid) were significantly upregulated in the NF group, whereas lipid metabolites (cholesterol, phosphatidylcholine, ceramide) and progesterone were remarkably elevated in the AF group. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed upregulation of lipid-related pathways in the AF group and FoxO signaling pathway in the NF group. These findings confirm that artificial feeds drive hepatic lipid metabolism reprogramming without altering growth, but induce obvious hepatic steatosis in mandarin fish. Our findings provide a metabolic foundation for optimizing artificial feed formulations to improve hepatic health and sustainable culture of mandarin fish.