Rice-fish co-culture system is an agricultural model that utilizes water resources for dual purposes, which is beneficial for stabilizing aquaculture while increasing grain production. The effects of different rice planting coverage rate (0%, 25%, 50%, and 75%) on grain yield and water quality were investigated for high-quality indica rice varieties Yuexiang 430 and Wushansimiao in fish ponds for breeding Australian freshwater lobsters. The aim is to provide scientific basis for optimizing rice-fish co-culture technology, improving production and efficiency of rice and fish. Concurrently, 30 rice varieties (with a planting coverage rate of about 37.1%) were used as experimental materials to screen rice varieties in fish ponds for breeding largemouth black bass. The results indicated that the rice yield of the treatments with 50% and 75% rice planting coverage was significantly higher than that of the treatment with 25% coverage. Specifically, Yuexiang 430 achieved the highest yield at 50% coverage, while Wushansimiao peaked at 75% coverage. The rice-crayfish co-culture led to significantly lower concentrations of NO₃^--N, NH₄⁺-N, NO₂^--N, COD, and BOD of pond water while compared to the 0% coverage. Similarly, the concentration of TOC of pond water exhibited the same trend during the early growth stages of rice, while pH value and dissolved oxygen levels have no significant difference during the rice growth period. Additionally, the rice varieties such as Huahang 48, Shuanghuangzhan, Qingxiangyousimiao, Yuexiang 430, Taifengyou 208, and Wushansimiao demonstrated superior performance with grain yields exceeding 5.50 t/hm² in rice-planting and largemouth bass co-culture system. In summary, a rice planting coverage rate of 50% under the rice-shrimp symbiotic mode has a relatively stable rice yield and a purifying effect on aquaculture water quality, making it more suitable for rice production in fishponds culturing Australian freshwater crayfish.