Astaxanthin (trans-Astaxanthin) is a keto-carotenoid in the terpenes class of chemical compounds. It is classified as a xanthophyll but it is a carotenoid with no vitamin A activity. It is present in most red-colored aquatic organisms. Astaxanthin has shown to mediate anti-oxidant and anti-inflammatory actions. It may be found in fish feed or some animal food as a color additive.