Effects of carotenoids on the cost of reproduction to a live-bearing fish

Chronic activities which increase metabolic rate, such as gestation, result in an increase in production of reactive oxygen species (ROS), increasing the risk of oxidative damage. Dietary carotenoids have been shown to play a role in protecting against oxidative stress. It was hypothesized that dietary carotenoids would help to reduce the metabolic costs associated with breeding in a live bearing fish. Guppies (Poecilia reticulata) were fed either a high (216 mg kg-1) or low (40 mg kg-1) carotenoid diet and divided into breeders and non-breeders. Sustained swimming performance was measured as an indirect measurement of oxidative damage/fitness. Prior to breeding, after 6 weeks on the experimental diets, males fed the high carotenoid content diet swam for longer. After 12 weeks on the diet and after breeding groups were allowed to breed, there was no effect of diet on swimming performance but non-breeders were able to swim for longer than breeders and females were able to swim for longer than males. In conclusion, breeding had an effect on swimming performance of guppies, and although a high carotenoid diet improved performance of males prior to breeding, carotenoids did not reduce the impact of breeding. Identifying dietary components that can help reduce the impact of breeding could improve pet fish health and welfare within the ornamental fish trade.