Effects of the use of synthetic astaxanthin in the feeding of Lophiosilurus alexandri, a neotropical siluriform fish.

Aiming to test the capacity of retention of carotenoids in tissues, Lophiosilurus alexandri juveniles were fed diets containing 0, 25, 50, 100, 200, and 400 mg/kg of synthetic astaxanthin for 62 days. The inclusion of astaxanthin did not result in significant differences in growth, weight gain, apparent feed conversion, and feed efficiency of the fish. Blood biochemistry and liver histology did not change with the different treatments. At the level of 100 mg/kg of inclusion, there were the highest levels of carotenoids in the blood, and muscle and the smallest difference between the muscle x integument ratio.