Abstract This study aimed to explore the efficient sewage discharge rhythm of pond cage culture tanks, ensuring the timely and effective removal of feces and residual bait in the tanks while reducing the energy consumption of sewage discharge equipment, thus safeguarding the water quality in the culture tanks. To this end, two stocking densities (1000 fish/tank and 600 fish/tank) were adopted to conduct culture experiments of Micropterus salmoides (largemouth bass) and sewage discharge tests for the culture tanks. Taking the Total Suspended Solids (TSS) concentration and turbidity of the water at the sewage outlet as the test indicators, the variation law of water quality at the sewage outlet after feeding was studied. The results showed that after the start of feeding, the TSS concentration and turbidity of the water at the sewage outlet increased sharply, and did not stabilize until 7 hours after feeding. On this basis, with the goal of achieving no significant difference in ammonia nitrogen content between the water at the sewage outlet of the culture tanks and the external pond water, optimization experiments of different sewage discharge rhythms were carried out within 1-7 hours after feeding. The results indicated that short-term and multiple sewage discharges were more conducive to improving the water quality in the culture tanks, and different stocking densities required different sewage discharge rhythms:For the stocking density of 1000 fish/tank, the sewage discharge rhythm should be "5 minutes of sewage discharge at 2 hours after feeding, 3 minutes of sewage discharge at 4 hours after feeding, and 3 minutes of sewage discharge at 7 hours after feeding"; For the stocking density of 600 fish/tank, the sewage discharge rhythm should be "5 minutes of sewage discharge at 3 hours after feeding and 3 minutes of sewage discharge at 5 hours after feeding". Verification experiments were conducted, and the results showed that under the optimized sewage discharge rhythm in this study: For the 1000 fish/tank group, the cumulative removal rates of TSS concentration and turbidity increased to 98.46% and 97.86%, respectively, both higher than the 26.83% and 18.32% of the traditional sewage discharge method (5 minutes of sewage discharge at 2 hours after feeding); For the 600 fish/tank group, after the first two sewage discharges, the cumulative removal rates of TSS and turbidity reached 94.58% and 96.86%, respectively, which were also significantly higher than the 24.32% and 19.36% under the traditional sewage discharge method.