[Background] Carbon sink is the process, activity, or mechanism of capture carbon dioxide from atmosphere, and the concept can also be applied to fisheries, creating "carbon sink fishery".[Method] The carbon of capture is realised by the growth of fish, that feed on natural food. In fish culture, the carbon inputs for fish farming is usually not considered. Silver (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) are filtering fish and live on plankton. Mandarin fish Siniperca chuatsi is piscivorous, and lives on fish that feed on natural food, so it can be considered that the carbon, bound through individual growth, comes from natural food. In addition, we assumed that 20% of the total production of grass carp (Ctenopharyngodon idellus), crucian carp (Carassius auratus), and common carp (Cyprinus carpio) from aquaculture feeds on natural food. Assuming that 50% of the total crab population kept in aquaculture also feeds on natural food. In order to calculate the carbon sink capacity of freshwater aquaculture, they were analyzed based on the data of "Chinese Fisheries Statistical Yearbook" from 2011 to 2015.[Result] The annual carbon sink capacities of the national freshwater aquaculture were 1.362, 1.405, 1.460, 1.530 and 1.645 million tons from 2010 to 2014, respectively, with an average of 1.480 million tons. The annual carbon sink capacities for national freshwater fishing were 0.293, 0.287, 0.296, 0.297 and 0.296 million tons, respectively, with an average of 0.294 million tons.[Conclusion and significance] With shrinking resources, the development of the carbon sink capacity for freshwater aquaculture will increase in importance.