Physiological Response of Asian Seabass Reared in Recirculating Aquaculture System under Different Stocking Densities

Background: There is a gap that we will need to use innovative solutions to produce more food and nutrition. RAS is a continuous water-flowing system that can induce schooling behaviour, a phenotypic character seen in Asian seabass that could help cut down cannibalism at a certain level. Stocking density is one of the critical factors affecting the growth, survival and health status of animals, which can influence the antagonistic behaviour pattern, hierarchical phenomena and cannibalistic nature of Asian seabass during the early life stage. Methods: A 60-day trial was conducted to evaluate the effect of different stocking densities (70, 140, 210, 280 and 350 fish/m3) on biochemical and stress gene expression of Asian seabass (Lates calcarifer) reared in Recirculating Aquaculture System by following a completely randomized design with four replications. Result: The study found that fish reared at 350 fish/m3 had significantly higher haemoglobin and red blood cells. In the case of biochemical parameters, total protein, Albumin and Globulin were lower in 70 fish/m3 and Blood Urea Nitrogen, cholesterol and triglycerides were significantly higher in 350 fish/m3 treatment. The relative gene expression of HSP70, HSP90A and GST was significantly upregulated with the increasing stocking density. The study suggests that the rearing of Asian seabass at a stocking density of 70 fish/m3 in a recirculatory aquaculture system could improve the growth performance and metabolic and molecular activities of the fish.