Effect of Astacin on Growth and Color Formation of Juvenile Red-White Ornamental Carp (Cyprinus carpio var. koi L)

Abstract

Body color is an important quality and determines the value of koi. Fish are unable to fully synthesize carotenoid pigments. Therefore, carotenoid needs to be added to their diets. This study determined the effect of astacin on the growth and body color enhancement in healthy red-white ornamental carp (Cyprinus carpio var. koi). Fish were fed diets containing 0 (control), 50, 100, 150, 200, or 250 mg astacin/kg diet for 8 weeks. At the end of the experiment, samples of red-white, red, and white skin, head, scales, and fin ray were collected for carotenoid content analysis and visual observation. Fish weight and specific growth rate were significantly higher in fish fed the 150, 200, and 250 mg diets than in fish fed the control while the feed conversion rates in the 200 and 250 groups were significantly lower than in the control. Carotenoid deposition in the skin, head, scale, and fin ray of fish fed diets containing astacin was significantly higher than that those fed the control. In addition, a higher astacin content resulted in a brighter body color. The highest carotenoid concentration was achieved when 250 mg astacin/kg feed was added. Astacin was mainly deposited in the skin, scales, and head.