Astaxanthin is a red pigment occurring naturally in a wide variety of living organisms. Although the word astaxanthin may not be commonly encountered in everyday speech, the pigment itself is found in many human foods, and you are quite likely to be consuming it in your diet already. Most crustaceans, including shrimp, crawfish, crabs and lobster, are tinted red by accumulated astaxanthin. The coloration of fish is often due to astaxanthin; the pink flesh of a healthy wild salmon is a conspicuous example. In commercial fish and crustacean farms, astaxanthin is commonly added to feeds in order to make up for the lack of a natural dietary source of the pigment. Not only does astaxanthin provide for pigmentation in these animals, it also has been found to be essential for their proper growth and survival.

Astaxanthin is one of a group of natural pigments known as carotenoids. In nature, carotenoids are produced principally by plants and their microscopic relatives, the microalgae. Animals cannot synthesize carotenoids, thus ultimately they must obtain these pigments from the plants and algae that support their food chains.

The astaxanthin molecule is similar to that of the familiar carotenoid beta-carotene but the small differences in structure confer large differences in the chemical and biological properties of the two molecules. In particular, astaxanthin exhibits superior antioxidant properties to beta-carotene in a number of studies being carried out. The positive effects of astaxanthin on farmed fish and crustaceans have been recognized for years.