Oral administration of different level of Dunaliella salina on skin carotenoids and color of Heros serverus

    Fish color is one of the most important indicators of marketing process in aquaculture. In this study, the effect of food supplementation with different level of Dunaliella salina on skin carotenoid level, skin and fins coloration in H. serverus were investigated. One hundred and eighty H. severus weighing 27±0.5g  were randomly divided to four groups in triplicate: Groups 1 (G1) were fed with basal diet, group 2 (G2), group 3 (G3) and group 4 (G4) fed with basal diet supplemented with 50, 100 and 200 ­mg kg^-1 D.salina, respectively. Following 6 weeks administration of experimental foods, digital photos were taken from each group and skin samples were taken after euthanasia. Skin beta carotene rate as well as skin and fins coloration pattern were compared among groups (a*, ­b*, Hue, L* and Chroma). Results showed that skin beta carotene rate significantly increased  in G2, G3 and G4 in comparison with control (P<0.05), and the highest rate was 4.06±0.45 mg kg^-1 in G4 . There was no significant difference recating to color indicators in skin area between the groups (P>0.05). In the fin area a* value significantly increased in G2 and G3 compare to control also Hue and b* value significantly decreased in G2 and G3 compare to control (P<0.05). Chroma value significantly increased in G3 compare to other groups (P<0.05). No significant difference were observed in L* value between the groups (P>0.05). Regarding to the availability and low cost of D.salina as well as possibility of its mass production, D.salina can be used as an natural source of carotenoid for improving color and carotenoid level in fish.