European sea bass (Dicentrarchus labrax) fingerlings (0.4 ± 0.05 g
initial weight) were fed on 4 diets contain 0, 60, 80 and 100 mg axtaxanthin
/kg diet for 60 days. Results showed marked enhancement in fish growth,
feed utilization efficiency, survival rate and fish protein content when 100 mg
astaxanthin was supplemented in fish diet. The activities of hepatic
antioxidation enzymes; superoxide dismutase (SOD) and glutathione
peroxidase (GPx) have reduced as the level of dietary astaxanthin increased.
Results showed simultaneous gradual increase in intestinal mucosal
phagocytic and lysozyme activities as astaxanthin inclusion level elevates in
diets indicating effective role of astaxantin as an immunostimulant agent in
sea bass diet. By the end of the trial, fish were exposed to a sudden drop in
water salinity (37 to 0.3‰) and that continued for 24 hours period. Survival
rate was significantly the highest in fish that consumed 100mg/kg diet and
when compared with control group an increment of 36.9% was recorded
suggesting an improvement in fish tolerance against osmotic stress. Results
demonstrate that astaxanthin is a qualified feed additive for sea bass.