Some dietary carotenoids, of which astaxanthin is their terminal carotene for storage, have been effectively used in enhancing the external colors of crustacean to give a healthy and natural image of the cultured animal for high market price. Such high positive correlation between dietary carotenoids concentration and body carotenoids content has been well established. Efficacy in terms of cost and time remains the key concern for pigmentation study. Beyond that 'cosmetic' role, other important biological roles of carotenoids in cultured shrimp and prawn have brought keen interests in the recent decades especially when high mortality and stunt growth are encountered during culture processes. Dietary astaxanthin supplement has demonstrated survival improvement in the benthic penaeids such as kuruma shrimp and tiger shrimp. It was first postulated that body astaxanthin may serve as an intracellular oxygen reserve, allowing the shrimp to survive under the hypoxic conditions in pond bottom. Further studies showed that the increase of body astaxanthin content in shrimp through dietary supplementation enhanced its antioxidant capacity and stability in metabolic response and immune response, concomitantly, its resistance to hypoxia, thermal and osmotic stress, ammonia toxicity, and pathogenic vibrio challenge. In shrimp, dietary carotenoids increase its body carotenoids content and antioxidant capacity which in turn equips itself with the resistance against those physical, chemical and pathological stresses. Since such protection effect becomes pronounced especially when stress is encountered, carotenoids have played well their nutraceutical (nutritional + pharmaceutical) roles.