Mandarin fish (Siniperca chuatsi) is a highly valuable freshwater carnivorous fish species that is extensively cultured in China. The pyloric caecum is a unique structure in the digestive tract of carnivorous fish that plays a crucial role in the digestion and absorption of food proteins and lipids. However, the effects of the pyloric caecum on digestion and absorption remain unclear. In this study, we aimed to investigate the role of the pyloric caecum in the digestion and absorption of sugars in mandarin fish. Through a feeding experiment with mandarin fish, we compared and analyzed the blood glucose level, glycogen content, amylase activity, and amylase (Amy) mRNA, Na⁺/glucose transporters 1 (Sglt1) mRNA and glucose transporter 2 (Glut2) mRNA expression in the pyloric caecum, proximal intestine, and mid-intestine after feeding for 0 to 16 h. The results indicated that following feeding, the trends in glycogen content, amylase activity, and Amy mRNA expression were consistent, with all showing an increasing and then decreasing trend and a peak at 6 h. Moreover, the values were significantly higher from 4 to 12 h compared to the other time periods. During other periods, amylase activity and Amy mRNA expression did not significantly differ between the pyloric caecum and proximal intestine; however, both were significantly higher than those observed in the mid-intestine. The changes in blood glucose levels were consistent with the glycogen content trends in the pyloric caecum, proximal intestine, and mid-intestine after feeding for 0 to 16 h. When blood glucose levels increased, Sglt1 may mainly play a key role in glucose absorption, while the transport of sugars may be mediated by Glut2. The expression of Sglt1 mRNA peaked at 1 h after feeding in the pyloric caecum, proximal intestine, and mid-intestine. The expression of Glut2 mRNA in the pyloric caecum was significantly higher than that in the proximal intestine and very significantly higher than that in the mid-intestine. Additionally, the Glut2 mRNA expression levels were significantly greater at 4 h to 12 h compared to the other time intervals. In conclusion, the pyloric caecum of mandarin fish is one of the main digestive and absorptive tissues, and the peak period for sugar digestion and absorption was between 4 h and 12 h after feeding.