Abstract Aeration plug-flow devices (APFDs) have been used with recirculating aquaculture systems (RASs) to simultaneously improve water circulation and oxygenation. However, it is still unclear how aeration flow rates affect fish growth for better extension and application. Thus, a series of experiments were conducted to explore the water quality and growth performance of tilapia (Oreochromis niloticus, average body length 8.93 ± 0.34 cm, average body weight 23.61 ± 3.50 g) using three self-designed RASs with APFDs with three aeration flow rates for 56 days. Aeration flow rates were applied in triplicate with the values of 0 L/min (control treatment, C), 30 L/min (moderate treatment, M) and 50 L/min (large treatment, L). The results showed that the water velocity and dissolved oxygen (DO) concentration increased with the increase in aeration flow rates, and the non-aerated condition resulted in a low DO and low pH but higher values of N H 4 + (3.22 ± 0.17 mg/L) and P O 4 3 − (5.78 ± 0.13 mg/L) for treatment C on the 56th day. The tilapia’s length gain rate, weight gain rate and specific growth rate for treatment M on the 56th day were 49.90 ± 4.07 %, 235.70 ± 19.80 % and 2.81 ± 0.54 %/d, respectively, which were 11.07 %, 20.2 %, and 41.4 % higher than that for treatment C, and increased compared to treatment L by 2.04 %, 19.5 %, and 8.49 %. Additionally, more nutrients (i.e., total protein, total cholesterol, glucose) accumulated in tilapia serum for treatment M compared to those in other treatments. Multiple regression analysis showed that growth rates are correlated with DO, N O 3 − and P O 4 3 − . This study gave a new try by combining water circulation and oxygenation into RASs with APFDs, and it is worth popularizing and applying to reduce the operational costs.

中文翻译：

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用于循环水产养殖系统的曝气推流装置对罗非鱼 Oreochromis niloticus 生长的评估

摘要 曝气推流装置 (APFD) 已与再循环水产养殖系统 (RAS) 一起使用，以同时改善水循环和氧化。然而，目前尚不清楚曝气流速如何影响鱼的生长以更好地推广和应用。因此，使用三个自主设计的 RAS 和 APFD 和三个曝气流进行了一系列实验来探索罗非鱼（Oreochromis niloticus，平均体长 8.93 ± 0.34 cm，平均体重 23.61 ± 3.50 g）的水质和生长性能利率为 56 天。曝气流速以 0 L/min（对照处理，C）、30 L/min（中等处理，M）和 50 L/min（大处理，L）的值一式三份应用。结果表明，水速和溶解氧（DO）浓度随着曝气流量的增加而增加，非曝气条件导致低DO和低pH值，但NH 4 +值较高（3.22±0.17 mg/ L) 和 PO 4 3 - (5.78 ± 0.13 mg/L) 在第 56 天用于治疗 C。第56天处理M的罗非鱼体长增加率、体重增加率和比生长率分别为49.90±4.07%、235.70±19.80%和2.81±0.54%/d，分别为11.07%、20.41.4% % 高于处理 C，与处理 L 相比增加了 2.04%、19.5% 和 8.49%。此外，与其他处理相比，处理 M 的罗非鱼血清中积累了更多的营养素（即，总蛋白、总胆固醇、葡萄糖）。多元回归分析显示增长率与DO、NO 3 - 和PO 4 3 - 相关。本研究将水循环和充氧结合到RAS与APFD中进行了一次新的尝试，值得推广应用以降低运营成本。