Dietary carotenoids do not improve motility or antioxidant capacity in cichlid fish sperm

Carotenoids may act as antioxidants under many circumstances. We examined the importance of carotenoids as antioxidants in the gonads of male convict cichlids (Amatitlania nigrofasciata), a species in which males lack the carotenoid-based breeding coloration that characterizes females. Male fish were fed one of four diets that included different combinations of xanthophyll and carotene carotenoids, and then we measured carotenoid concentration of the gonads, gonadosomatic index (GSI), sperm motility, and the antioxidant capacity of the gonads. Significant differences were found in gonadal carotenoid content among treatment groups, suggesting that dietary carotenoids were indeed sequestered in the gonads. There were no differences among diet groups, however, in GSI, sperm motility, or gonadal antioxidant capacity. These findings suggest that carotenoids are required only in small amounts in the testes of male convict cichlids or that they play a limited role in protecting sperm from oxidative damage.