Here, we aimed to investigate whether resveratrol (RSV) can ameliorate high-fat diet (HFD)-induced metabolic disorder in fish. Blunt snout bream (Megalobrama amblycephala) with average weight 27.99 ± 0.56 g were fed a normal fat diet (NFD, 5% fat, w/w), a HFD (11% fat), or a HFD supplemented with 0.04, 0.36, or 1.08% RSV for 10 weeks. As expected, fish fed a HFD developed hepatic steatosis, as shown by elevated hepatic and plasma triglycerides, raised whole body fat, intraperitoneal fat ratio and hepatosomatic index, and increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). RSV supplementation lessened increases in body mass, whole body fat, and intraperitoneal fat, and alleviated development of hepatic steatosis, elevations of plasma triglyceride and glucose, and abnormalities of ALT and AST in HFD-fed fish. RSV supplementation increased SIRT1 messenger RNA (mRNA) expression and consequently hepatic mRNA expression of adipose triglyceride lipase (ATGL), carnitine palmitoyltransferase (CPT1a), and microsomal triglyceride transfer protein (MTTP), implying upregulation of lipolysis, β-oxidation, and lipid transport, respectively, in the liver. Conversely, hepatic lipoprotein lipase (LPL), sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), and ATP citrate lyase (ACLY) mRNA expression were decreased, implying suppression of fatty acid uptake, lipogenesis, and fatty acid synthesis. Additionally, RSV downregulated glucokinase (GCK) and sodium-dependent glucose cotransporter 1 (SGLT1) and upregulated glucose transporter 2 (GLUT2) mRNA expression, thus restoring normal glucose fluxes. Thus, RSV improves lipid and glucose metabolisms in blunt snout bream, which are potentially mediated by activation of SIRT1.