Size‐assortative Monogamy and Paternal Egg Care in a Coral Goby <i>Paragobiodon echinocephalus</i>

Abstract

Abstract Paragobiodon echinocephalus (Pisces; Gobiidae) inhabits the branching coral Stylophora pistillata. Only the largest two fish bred in a coral irrespective of group size, which was larger in larger corals. Breeding pairs consisted of a male and female of similar body size. Eggs were spawned on the coral branch and guarded by the male parent for about 4 days until hatching. Successive spawning occurred usually one day after hatching. The reproductive success of a pair, measured as the number of newly hatched larvae, was positively correlated with the body size of the male as well as the female. That is, not only female fecundity but also male ability of egg guarding were limited by body size almost equally. This should promote size‐assortative monogamy in the goby.