The antioxidant activity of astaxanthin was reported to be ten times stronger than that of other carotenoids, viz., zeaxanthin, lutein, canthaxanthin and β-carotene. This particular carotenoid is of considerable academic and practical interest not only because of its abundance in nature but also high economic value as a pigment in fish feeds. It is widely used as an additive in fish feed to enhance the colour of pond-bred salmonids.