| Studies were implemented,which using the enclosed industrialized recirculating aquaculture systems designed by our research group to cultivate Larimichthys crocea and Anguilla rostrata（from South America）.By the application of moving bed biofilm reactor and O3/UV combination unit in water treatment system,water treatment efficiency and aquaculture water quality were improved,and diseases were effectively prevented,moreover,both cultivation survival rate and breed benefit were increased.The research results should provide guidance for aquaculture in recirculating aquaculture system.The main research contents were as follows:（1）Larimichthys crocea larvae were stocked,whose size was 1.82±0.05 g/ind at three different densities（350 ind/m3,400 ind/m3and 450 ind/m3）in 9 barrels,and each density with 3barrels.The trial period was 180 days.The results showed that:400 ind/m3was the optimum culture density,which average survival rate was 83.58%±1.03%,average capture individual weight at 95.42±1.27 g,individual weight increased at 0.52±0.007 g/d,and feed conversion ratio（FCR）was 1.28±0.07.Average survival rate,capture individual weight and individual weight increased at the density of 400 ind/m3were significantly higher than those at 450 ind/m3density by 11.16%、27.51%and 28.07%respectively（P<0.05）.FCR at the density of 400 ind/m3was significantly lower than those at 450 ind/m3density by 22.89%（P<0.05）.But there was no significant difference between 400 ind/m3and 350 ind/m3density group（P>0.05）.During the period,water quality concentrations of total ammonia nitrogen（TAN）and NO2-N were as low as0.126±0.072 mg/L and 0.047±0.047 mg/L respectively in 400 ind/m3density group.Both concentrations of TAN and NO2-N in 400 ind/m3group were significantly lower than those in450 ind/m3group by 25.3%and 41.0%respectively（P<0.05）.But there was no significant difference between 400 ind/m3and 350 ind/m3density group（P>0.05）.No parasitic diseases and bacterial diseases occurred during the period.In summary,Pseudosciaena crocea cultivation in the recirculating aquaculture system,resulted in not only water saving and effluents reduction,but also effective prevention and control disease,and survival rate was greatly increased.（2）Anguilla rostrata glass eel was stocked,whose size was 7143 ind/kg at the density of4630 ind/m3in 16 cement pools,which 13 pools with recirculating water as the treatment group and the other 3 pools without recirculating water as the control group.The trial period was 60days.The results showed that:Anguilla rostrata glass eel cultured in the recirculating aquaculture system,which average survival rate was 99.68%±1.17%,average capture individual weight at 3.34±0.06 g,individual weight increased rate at 5.43%±0.03%,the specific growth rate at 5.28%±0.14%,and FCR was 4.95±1.35.Average survival rate,capture individual weight,the specific growth rate and individual weight increased rate in the treatment group were significantly higher than the control group by 12.19%、40.33%、17.01%、18.39%respectively（P<0.05）;FCR in the treatment group was significantly lower than the control group by 12.70%（P<0.05）.During the period,water quality concentrations of TAN and NO2-N were as low as 0.456±0.125 mg/L and 0.089±0.084 mg/L respectively in the treatment group.Both concentration of TAN and NO2-N in the treatment group were very significantly lower than those in the control group by 79.1%and 84.8%respectively（P<0.01）.The average removal rate of TAN was 89.9%±9.8%,the average removal rate of NO2-N was 90.8%±6.8%.No parasitic diseases and bacterial diseases occurred during the trial,but the control group broke out tail-rot disease several times.（3）Anguilla rostrata elvers were stocked,whose size was 296 ind/kg at the density of 10kg/m3in 16 cement pools,which 13 pools with recirculating water as the treatment group and the other 3 pools without recirculating water as the control group.The trial period was 90 days.The results showed that:Anguilla rostrata elvers cultured in the recirculating aquaculture system,which average survival rate was 99.72%±1.14%,average capture individual weight at 13.16±0.06 g,individual weight increased rate at 1.53%±0.56%,the specific growth rate at 1.52%±0.14%,and FCR was 1.4±0.15.Average survival rate,capture individual weight,the specific growth rate and individual weight increased rate in the treatment group were significantly higher than the control group by 51.49%、57.98%、25.92%and 80.95%respectively（P<0.05）;FCR in the treatment group was significantly lower than the control group by 18.60%（P<0.05）.During the period,water quality concentrations of TAN and NO2-N were as low as 0.403±0.117 mg/L and 0.137±0.046 mg/L respectively in the treatment group.Both concentration of TAN and NO2-N in the treatment group were very significantly lower than those in the control group by76.8%and 73.2%respectively（P<0.01）.The average removal rate of TAN was 88.1%±1.13%,the average removal rate of NO2-N was 94.3%±1.05%.No parasitic diseases and bacterial diseases occurred during the period,but the control group broke out tail-rot disease and red-head disease several times. |
