Effects of Vegetable-Fish Co-Culture on CH4 and N2O Emissions from an Aquaculture Pond

Freshwater aquaculture is an important source of greenhouse gas (GHG) emissions. GHG emissions are expected to lead to global warming and climate change. A reduction in GHG emissions is urgently required for the sustainable development of freshwater aquaculture. In this study, a laboratory-scale experiment was conducted to analyze the effects of a vegetable-fish co-culture on CH4 and N2O emissions from a freshwater aquaculture pond. The results show that the co-culturing of yellow catfish with pak choi (PC-F) or water spinach (WS-F) significantly reduced the N2O emission from the aquaculture pond by 60.20% and 67.71%, respectively, as compared with a yellow catfish monoculture (F). However, the co-culture of these two vegetables did not affect the level of CH4 emissions. The reduction in N2O emissions was primarily attributed to the decrease in the concentration of N2O and NO3- in the water. The overall global warming potential (GWP) of CH4 and N2O was significantly reduced by 19.1% with PC-F compared to F, but it did not significantly differ between WS-F and F. PC and WS cultivation improved the food yield by 1555.52% and 419.95% compared to F, respectively. Consequently, the GHG emissions intensity (GHGI) under PC-F and WS-F decreased by 96.15% and 80.77% compared to F, respectively. Altogether, the results highlight that a vegetable-fish co-culture is likely an efficient system for mitigating GWP per unit of food yield in freshwater aquaculture ponds. These results can provide a reference for the mitigation of GHG emissions from freshwater aquaculture.