Study on the effect of semi-closed recirculating aquaculture system for European eel

To improve the eel farming efficiency and reduce the environmental pollution, a low -cost and environmentally friendly semi-closed recirculating system for eel was created, and blackie eels were cultivated in this system. The results showed that, the concentration of ammonia nitrogen, nitrite nitrogen, nitrite nitrogen in the recirculating system was 0.73~11.14 mg/L, 0.01~2.2 mg/L, 5.00~26.89 mg/L, respectively. In addition, when DO, pH value, water temperature and average daily water exchange rate were maintained at 4.7 ~5.1 mg/L, 6.9 ~7.6, 21 ~22益, 23.6% respectively, after 75 d for feeding, the average body weight of eel increased from 10.8 g to 16.2 g, the survival rate was 98.72%, the SGR was 0.54%/d, and the FCR was 2.06. This recirculating system has some advantages such as better water quality, easier transformation and operation, better water saving in winter.