Protective effect of shrimp carotenoids against ammonia stress in common carp, Cyprinus carpio.

This study is aimed at evaluating the protective effect of shrimp carotenoids on ammonia stress in common carp. Crude carotenoid extract from shrimp exoskeleton, astaxanthin and astaxanthin ester fractionated from crude extract was fed to the common carp fingerlings at 100 and 200ppm concentration by incorporating carotenoids into feed. Experimental and control fish were then exposed to sublethal dose of ammonia. Serum total antioxidant status (TAS), activities of superoxide dismutase (SOD) and catalase were measured to determine the effect of dietary carotenoid on defense status of fish. Activities of aspartate transaminase (AST) and alanine transaminase (ALT) were measured to determine the protective effect of carotenoids against tissue damage caused by the ammonia stress. TAS, catalase and SOD activity was higher in tissues from fish fed with the diet containing astaxanthin rich and astaxanthin ester rich extract compared to fish fed with control diet. TAS reduced in the tissues considerably after exposure to ammonia. However, TAS was still higher in tissues from fish fed with carotenoid containing diet than in tissues from fish fed with control diet. Eventhough there was an increase in the activities of ALT and AST due to stress by ammonia toxicity in all groups, fish fed with astaxanthin extract had lower activities and also prevented lipid peroxidation in the tissues. In conclusion, shrimp carotenoid increased the resistance of common carp fingerlings to ammonia induced stress.