Effects of astaxanthin and Dunaliella salina on skin carotenoids, growth performance and immune response of Astronotus ocellatus

In this study, Astronotus ocellatus were fed with food supplemented with Dunaliella salina (a natural beta-carotene source) or astaxanthin (synthetic pigment), and their effects on fish skin carotenoids, growth indices and immune responses were evaluated. 135 A. ocellatus, weighing 25.6 +/- A 0.6 g, were randomly divided into three groups with three replicates (15 fish in each replicate). Group 1 and 2 were fed with a diet supplemented with 200 mg/kg astaxanthin or D. salina, respectively. Control group received the same diet without supplemented carotenoids. After 50 days, the growth indices were compared with the groups. Blood, mucus and skin samples were taken from each group. The immunological parameters of dietary D. salina and astaxanthin were studied in terms of serum and mucus lysozyme and bactericidal activity, as well as resistance against Aeromonas hydrophila infection. Carotenoid content of skin was assayed as well. Results showed that growth indices increased significantly in fish fed diet supplemented either with astaxanthin or D. salina (P < 0.05). Serum and mucus lysozyme and bactericidal activity increased in D. salina and astaxanthin groups (P < 0.05). Skin carotenoid content was statistically higher in astaxanthin group (6.48 +/- A 0.84 mg g(-1)) and D. salina group (4.89 +/- A 0.83 mg g(-1)) compared with the control group (3.05 +/- A 0.32 mg g(-1)) (P < 0.05). Rate of mortality following the challenge with A. hydrophila was significantly lower in D. salina group (50 +/- A 10) and astaxanthin (56.7 +/- A 5.8) group compared with control group (76.7 +/- A 5.8) (P < 0.05). Conclusively, D. salina and astaxanthin as a food additive can affect positively the growth and immunological parameters as well as skin carotenoid of A. ocellatus.