Effect of water flow on growth and metabolism in Sebastes schlegelii

The supplement of aquatic biological resources through the release of indigenous aquatic animals is a crucial measure to maintain local biodiversity and promote sustainable environmental development. The present study aims to investigate the response of black rockfish, a site-specific species, to different water flow conditions, considering the significance of water flow. Juveniles were exposed to four water flow velocities for 45 days, and their growth and metabolism were monitored. The findings reveal that black rockfish showed significantly better growth performances in all water flow treatment groups than the Control group, with the optimal flow rate observed at 1.5 BL/s. In the Control and water flow treatment groups, amino acids and fatty acids were the primary up-regulated differential metabolites, with the highest amino acid being Gly-Ala-Pro-Met-Phe-Val-NH2 and the highest fatty acid being LPC. Notably, nicotinamide was the only metabolite significantly down-regulated. The benefits of water flow were attributed to the high protein utilization and immune capacity of black rockfish. However, water currents exceeding the comfort range resulted in faster mobilization of energy-supplying substances and an increase in oxidative stress in juveniles. Glutathione may be a potential biomarker to identify high water flow stress in black rockfish juveniles. This study provides a comprehensive insight into the metabolic responses of black rockfish to various water flow conditions by assessing its multiplatform, untargeted metabolomic profiles in combination with growth performance. The outcomes of this study have both fundamental and applied significance in improving fish welfare in commercial aquaculture and enhancing the survival of juveniles released into the wild.