A 10-wk feeding trial to determine the effect of daily feeding ratio on growth and body composition of subadult olive flounder fed the extruded pellet (EP) was performed during the summer season. Thirteen flounder (an initial body weight of 319 g) per tank were distributed into fifteen 500-L flow-through tanks. Five treatments of feeding ratio in 5% decrement were prepared in triplicate: 100 (satiation), 95, 90, 85, and 80% of satiation. Fish in the control group (100% of satiation) were hand-fed to apparent satiation twice a day. Then, feed allowance in the rest of the four groups was determined based on average feed consumption of fish in the control group. Weight gain of fish fed to 100% of satiation was significantly (P < 0.05) higher than that of fish fed to 85 and 80% of satiation but not significantly (P > 0.05) different from that of fish fed to 95 and 90% of satiation. Serum total protein, glucose, and glutamic pyruvic transaminase were not significantly (P > 0.05) affected by feeding ratio but triglyceride and glutamic oxaloacetic transaminase were. In considering these results, it can be concluded that optimum daily feeding ratio for growth of subadult olive flounder seemed to be 90% of satiation when fish were fed the EP twice a day during the summer season.