The effects of oxygen supplementation on growth and survival of rainbow trout (Oncorhynchus mykiss) in different stocking densities

In this study, the effects of oxygen supplementation in different stocking densities of rainbow trout (Oncorhynchus mykiss) on the specific growth rates (SGR), feed conversion ratios (FCR) and survival rates were investigated in a commercial-scale culture system. High density cultures were maintained in a total of nine (12 m3) flow-through systems supplemented with O2. Initial stocking rates for 3 different treatments with three replicates were 26.88±0.30 (low density), 36.72±0.26 (medium density) and 55.03±0.14kg m-3 (high density), corresponding to a total of 5800, 8000 and 12000 fish/tank, respectively. Water flow rate for each tank was maintained at 11±1.1 L sec-1 (660 L min-1) over the study period for each raceway, and the temperature was 12.3±0.8°C throughout the experimental period. At the end of the study, there were no significant differences in the survival rates and SGR among treatments (p>0.05). However, FCR was negatively affected in the high density treatment (p<0.05). Overall, our results indicated that oxygen supplementation supported fish growth and survival in high stocking densities. However, high production cost is prohibitive and further studies are required to reduce costs.