Currently, the recirculating aquaculture system (RAS) is considered an alternative system to mitigate the potential environmental deterioration occurred by traditional culture systems. The RAS is a closed system that can secure the independency from the external environments and can efficiently control the internal environments, thus enhancing productivity by intensification. However, intensification during the production process has often drawn concerns in terms of animal welfare. Good welfare is reflected in the culture animal’s conditions and tolerance to the infectious matters or stressors. So, in this study, we evaluated the effects of stocking density on the growth performance and haematological changes of olive flounder.
An 8-week growth experiment was conducted with initial stocking densities of 3.29, 4.84, 7.14, and 8.56 kg/m2 using juvenile olive flounder (59.7±3.5 g) in a RAS. An experimental RAS consisted of 12 square tanks (95 x 95 x 85 cm), two square tanks of moving-bead biofilter (100 x 100 x 100 cm), an UV sterilizer (80 W), a down-flow oxygen contactor, a centrifugal pump (290 L/min), and a drum filter (80 µm sieve). Water temperature was maintained at 25oC using two chillers (1 HP), and a submersible heater. Water turnover rate was set at 24 times/day and 10% of water were exchanged daily. Fish were fed a commercial feed (55% protein and 8% lipid) to apparent satiation twice a day.