System-specific aquaculture annual growth rates can mitigate the trilemma of production, pollution and carbon dioxide emissions in China.

The aquaculture sector faces a trilemma of simultaneously boosting production, decreasing nutrient discharges and reducing CO2 emissions. Here we evaluate the growth trajectories and ecological footprints of different aquaculture systems in China, considering both business as usual and ecological transformation scenarios, and anticipate the evolution of sustainable aquaculture in the post-carbon neutrality era. We explore a two-step approach involving ecological transformation and green aquaculture. By adjusting the annual growth rates of six out of nine aquaculture systems, energy use, nitrogen discharge, land use and freshwater usage per unit of mass gain could be reduced by 1.70%, 6.89%, 7.12% and 8.86%, respectively, by 2050 compared with the business as usual levels. Owing to changes in the energy supply mix in China, by 2050, the total CO2 emissions from aquaculture will only increase by 5.7% compared with the level in 2021. Once carbon neutrality is attained, the focus should shift to mitigating nutrient discharges. Our findings underscore the necessity for substantial improvement in the Chinese aquaculture development plan and offer a blueprint for sustainable aquaculture advancement for guiding policy and practice.