Costs and benefits of biparental mucus provisioning in discus fish (Symphysodon aequifasciatus)

We tested the manner in which the number of fry influences the costs and benefits of mucus provisioning in discus fish ( Symphysodon aequifasciatus ) via two experiments. In experiment-1, we found that fry grew more rapidly when they were raised with parents than when raised without parents, suggesting that fry benefits from the mucus provisioning by parents. In experiment-2, a reduction in the body weight of parents correlated with brood size. The growth rate of fry did not linearly correlate with brood size. We discuss the functions, costs, and benefits of mucus provisioning in discus fish.