Determining Oxygen Consumption of Indonesian Mahseer (Tor soro) Fingerlings at Different Size and Stocking Density

Understanding oxygen consumption in fish is one of the essential factors in the survival performance of cultured fish. As this information is established, the appropriate size and optimum stocking density of cultured fish reared in an aquaculture system can be determined for successful larval rearing of mahseer in a hatchery. This study aimed to obtain information on the oxygen consumption rate and critical oxygen level of Indonesian mahseer fingerlings at different sizes and stocking densities. This study was conducted in the Laboratory of Fish Reproduction and Genetics, which belongs to the Research Institute for Freshwater Aquaculture and Fisheries Extension, Bogor. A factorial design with two factors (size and stocking density) and three replications were employed to run the experiments. Oxygen consumption rate was measured using a closed respirometer system (volume: 1.4 L) Parameters observed during the study are oxygen consumption rate and critical oxygen level. The results showed that the highest oxygen consumption rate was found at the size of 6-8 cm at 9.52 mg O2/g/minute with a stocking density of 7 fish/1.4 L. Oxygen consumption rate of mahseer was increased with the increase of size and stocking density. In this experiment, the critical oxygen level of mahseer fingerlings was observed at 1.44 mg/L. The obtained critical oxygen consumption could be used as a reference to determine the amount of dissolved oxygen that could support the survival rate of mahseer. In rearing practice, it would be important information used for designing early warning and mitigating culture systems to avoid deterioration of dissolved oxygen levels in the water. Therefore, this study can be recommended for improvement mahseer rearing practice for better hatchery production with providing an appropriate oxygenation system for fingerling growth.