Dietary green tea extract improves growth performance, body composition, and stress recovery in the juvenile black rockfish, Sebastes schlegeli

In this study, we evaluated the effects of dietary green tea ethanol extract (GTE) supplementation on growth performance, body composition, and stress recovery of the juvenile black rockfish, Sebastes schlegeli. The fish (mean body weight, 8.1 ± 2.0 g) were fed fish meal diets that included 0 % (control), 1, 3, and 5 % GTE for 8 weeks. Weight gain, specific growth rate, feed efficiency, and protein efficiency rate were measured and compared among the fish in the different groups. The whole body and liver lipid compositions of fish fed the control diet were higher than those of the fish fed the GTE diets. Lysozyme activity in the plasma samples of fish fed the GTE diet showed an increasing trend in a dose-dependent manner. After administrating anesthesia (2-phenoxyethanol), the stress recovery time differed significantly between the control and the 3 and 5 % GTE diet groups and the mortality of fish fed on the GTE diet was significantly lower than that of the control group. In addition, plasma glucose levels in the fish fed the 3 % GTE diet showed a rapid recovery. Our results showed that the addition of GTE to the fish diet improved lipid utilization, lysozyme activity and stress recovery, and reduced total cholesterol levels in a dose-dependent manner.