Abstract: Grass carp Ctenopharyngodon idellus juveniles with body weight of 110±5g reared in a net cage of 1.0m×0.5m×1.0m were fed the basal diets supplemented with different levels ofhypericin （0%, 0.066%, and 0.132%）, chlorogenic acid （0%, 0.04%, and 0.08%） and scleroglucan （0%, 0.2%, and 0.4%） at water temperature of 25±2℃ for 35 days to evaluate the effects of the additives on growth performance and immune ftmction of the grass carp juveniles. The results showed that there were no significant differences in weight gain rate and specific growth rate in the juveniles in all experiments （P〉0.05）.However, the juveniles fed the diet containing 0.08% chlorogenic acid had significantly higher final body weight and hepatosomatic index than the juveniles fed the control diet did （P〈0.05）. All of the additives significantly enhanced the activity of alkaline phosphatase （AKP）, the peak value in the fish fed the diet supplemented with 0.08% chlorogenic acid, and no significant differences in AKP activity among all treatments. There was significantly higher activity of superoxide dismutase （SOD） in 0.132% hypericin group than that in the control, whereas there was no significant difference in SOD between the treatments and the control groups. The grass carp juveniles fed the diet supplemented with 0.2% scleroglucan had significantly higher lysozyme activity. The three additives were not found to affect significantly the content of malondialdehyde （MDA） in the serum.

Key words: hypericin, chlorogenic acid, scleroglucan, grass carp, growth, immune function