Comparison Between Recirculating Aquaculture System (RAS) Ponds and Earthern Aquaculture Ponds in Overwintering Juveniles of the Nile Tilapia, Oreochromis niloticus

The present study was carried out to compare the normal aquaculture in earthen ponds and the recirculating aquaculture system (RAS) in the overwintering of juvenile Nile tilapia, Oreochromis niloticus during the winter season. The overwintering experiment was carried out in 3 earthen ponds, each of 1 feddan (as replicates of a control group), and 5 concrete tanks (3*8*1 m³ concrete tanks, as replicates of recirculating aquaculture system, RAS treatment group) at an intensive fish farm in EL-Hammoul province, Kafr EL-Sheikh Governorate, Egypt. The experiment extended from December 2019 to April 2020. Results showed that the highest values of final length, length gain, average daily length gain, final weight, weight gain, average daily weight gain and specific growth rate were recorded for fish fingerlings reared in the control earthen ponds. These growth performance parameters were significantly varied between all concrete ponds of the recycle aquaculture system (RAS) treatment and that of the control ponds. On the other hand, the best results of food conversion ratio, feed efficiency ratio, and protein efficiency ratio were estimated to fish reared in RAS treatment ponds. The mortality rate was very high for the control fingerlings where it reached 80.33%, while it recorded only 9.1% for RAS treatment fishes. The economic analysis showed a positive net income value for RAS treatment ponds and a negative net income value for earthen ponds. The present study recommended overwintering the fingerlings of the Nile tilapia, O. niloticus in RAS ponds with controlled water temperature to enhance the fish culture in Egypt and prevent the terrible mortality of fish.