Juvenile turbot were obtained from a local commercial farm. The feeding trial was
conducted in an indoor flowing seawater system (5 L/min). Prior to the start of the experiment, the juveniles were reared for 2 weeks to acclimate to the experimental conditions. At the onset of the feeding trial, the fish were fasted for 24 h and weighed after being anesthetized with eugenol (1:10, 000). Fish of similar sizes (4.16 ± 0.01 g) were randomly distributed into 16 fiberglass tanks (120 L) and each tank was stocked with 25 fish. Each diet was randomly assigned to quadruplicate tanks. Fish were hand-fed to apparent satiation twice daily (06:30 and 16:30). At 30 min after feeding, the feed remnant was collected and counted, and the weight was calculated based on the average weight of 100 pellets. The feeding trial lasted 12 weeks. During the experimental period, the water temperature was 14 ± 0.5 °C, salinity 30 ± 0.5‰,
pH 7.5–8.0, and dissolved oxygen N7 mg L−1. At the end of the experiment, the fish were fasted for 24 h before harvest. After anesthetized with eugenol, fish were weighed and counted, and samples of whole fish, liver, gut, muscle, and serum from 5 fish each tank were collected,
frozen with liquid nitrogen and stored at −80 °C until use.