Six-week research was conducted to evaluate the effect of dietary supplementation of polyphenols on the performance
of Asian sea bass (Lates Calcarifer) juveniles (16.4 ± 0.49 g). The experimental diets included:
0 (control), 0.5, 1.0, 2.5, 5.0 g/kg 1 diet of a mixture of commercially available polyphenol (PMIX), made of
chestnut wood extract and olive extract (Silvafeed®TSP, and PhenoFeed®, respectively) The results indicate that
2.5 g/kg diet of PMIX, significantly affected the final weight, final length, specific growth rate, percent weight
gain, hepatosomatic index, and condition factor. Daily weight gain was significantly increased in fish fed with 2.5
and 5.0 g/kg diet of PMIX (P < 0.05). There were no significant differences between PMIX treatments and the
control group in biochemical blood parameters and body composition (P > 0.05). Analysis of the data shows that
mucus lysosomes activity was significantly increased in 0.5, 2.5, and 5.0 g/kg diet of PMIX groups. ACH50
increased in fish fed with 2.5 g/kg diet of PMIX. Total Ig levels in groups of 2.5 and 5.0 g/kg diet of PMIX were
better than the control (P < 0.05). Catalase (CAT) increased in fish fed by 5.0 g/kg diet of PMIX compared to
control fish (P > 0.05). The glutathione reductase (GR) and glutathione S-transferase (GST) activity in fish fed on
2.5 and 5.0 g/kg diet of PMIX was significantly higher than in the control fish (P < 0.05). There was a significant
decrease in Malondialdehyde (MDA) level in the liver of fish fed with 1.0, 2.5, and 5.0 g/kg diet of PMIX. These
results indicated that PMIX can be considered as a beneficial dietary supplement for improved growth parameter,
mucosal immune response, and liver oxidative status of the Asian sea bass juveniles.