Effects of hydrodynamic conditions at varying flow rates on growth, feeding behavior, and nutritional metabolism of silver pomfret (Pampus argenteus) in recirculating aquaculture systems

Recirculating aquaculture system (RAS) will become a primary cultivation method for silver pomfret in the future, so studying hydrodynamic characteristics in culturing tanks is essential for RAS construction of this fish. According to different jet flow rates of 0.1–1.6 m 3 /h, the flow distribution within the tank was simulated using FLUENT software. As jet flow rate increases, the surface flow field becomes increasingly chaotic, particularly in regions near water surface and at the locations of the jet nozzles. An increase in jet flow rate can significantly alter both range of jet diffusion and velocity distribution of water flows as well as that at the bottom of tank. The velocity at the bottom exhibits a circular distribution pattern. To further refine the appropriate flow rates, we set nine flow rate groups (jet flow rate =0.1–1.6 m 3 /h) to culture the fish for one week, and we found that the feeding rate and sewage discharge efficiency was both better in the range of jet flow rate from 0.4 to 0.8 m 3 /h than other groups, so we selected these rates for growth and metabolomics analysis. After 8 weeks long-term culture experiment in jet flow rate of 0.4, 0.6, 0.8 m 3 /h, the fish showed better growth performance and the accumulation of fatty acids and amino acids in 0.6 m 3 /h. The result indicated that the flow rate in RAS played key role on growth and nutrition composition of the fish, and the data can determine the available jet flow rate range of silver pomfret RAS, which can provide the reference for the construction of the RAS.