The effects of synthetic pigments on pigmentation of Pethia conchonius(Hamilton, 1822)

This study evaluated the effects of diets containing 20, 40, 60, 80 and 100mgkg(-1) diet astaxanthin or canthaxanthin on Pethia conchonius (Hamilton, 1822) pigmentation. A completely randomized experimental design was developed with ten treatments and three replicates. Three hundred rosy barb with a mean weight of 0.92 +/- 0.06g were assigned to thirty aquaria for period of eight weeks. Carotenoid contents of fish fed canthaxanthin were always lower than those fed astaxanthin. Yellowness (b*) was not affected by pigments. While Luminosity (L*) decreased in fish fed astaxanthin diets, this parameter increased by feeding on canthaxanthin. The most pronounced effect was higher a* values in fish fed astaxanthin. Astaxanthin retention rate was higher than that of canthaxanthin. The present results demonstrate that canthaxanthin cannot be considered as a proper replacement with astaxanthin. Inclusion of 80 and 100mg astaxanthinkg(-1) diet can be suitable dietary levels to ensure pigmentation and this condition may improve market value of rosy barb.