The biological performance of a pond recirculating aquaculture system for farming the giant freshwater prawn ( Macrobrachium rosenbergii )

Recirculating aquaculture systems are an important means of achieving sustainable development within the aquaculture industry. In this study, we established a pond recirculating aquaculture system (PRAS) for freshwater prawn ( Macrobrachium rosenbergii ) farming and evaluated its biological performance. In this system, conventional water quality indicators, antibiotics, heavy metals, and microbial community composition were monitored for four months. The results showed that the specific growth rate of the giant river prawn was 5.28% day -1 . The aquaculture effluent undergoes one cycle in the biological purification pond, reducing the levels of total nitrogen (TN, 13%), total phosphorus (TP, 50%), ammonia nitrogen (NH₄⁺-N, 34%), nitrite nitrogen (NO₂⁻-N, 30%), dissolved inorganic phosphorus (DIP, 57%), chromium (Cr, 34%), cadmium (Cd, 11%), iron (Fe, 25%), and manganese (Mn, 35%). In addition, the recirculating water system maintains antibiotic levels at a low level of enrofloxacin (ENR, 273.36~293.89 ng/L), other categories of antibiotics (0.54~171.58 ng/L). Biological treatment concomitantly increased the relative abundance of nutrient- and heavy-metal-removing bacteria (e.g., Pseudomonas ) in the water. Critically, correlation analysis shows that NH₄⁺-N, NO₂⁻-N, DIP, and Cr emerged as key drivers of microbial community structure. In summary, PRAS is an biologically optimised production model that is worthy of broader implementation.