An 8 week experiment was conducted to evaluate the effects of dietary fat on growth and on the accumulation of lipids and the expression of lipid metabolism-related microRNAs (miRNAs) and genes in grass carp (Ctenopharyngodon idella). Two diets (normal fat diet (NFD), 60 g/kg lipid content; high fat diet (HFD), 160 g/kg lipid content) were fed to triplicate groups of 35 fish [initial weight of (40.0 ± 0.5) g]. The results showed that increased dietary fat did not lead to significant differences in the feed conversion rate (FCR) and specific growth rate (SGR) (P > .05), but the HFD significantly increased the hepatosomatic index (HSI) (P < .05). The serum high density lipoprotein-cholesterol (HDLC) level was significantly increased in the HFD group (P < .05). Oil Red O staining showed that both the size and amounts of lipid droplets in the liver of fish fed a diet with 2 g/kg lipid content increased significantly. In the liver of fish fed with 160 g/kg dietary fat, the expression of mir-33a, mir-30, mir-122 and mir-16 significantly decreased (P < .05). In contrast, the expression of sterol regulatory element-binding transcription factor 1 (SREBP1), peroxisome proliferator-activated receptor gamma (PPARγ), liver X receptor alpha (LXRα) and ATP-binding cassette transporter A1 (ABCA1) significantly increased (P < .05). In conclusion, 2 g/kg dietary fat did not influence growth but altered the expression of miRNAs and genes related to lipid metabolism in the liver of grass carp, which caused severe lipid deposition.