Paternal mouthbrooding in the chocolate gourami Sphaerichthys osphromenoides (Osphronemidae)

Abstract

We examined sexual dimorphism and parental care in the chocolate gourami (Sphaerichthys osphromenoides) by visual observations, video recording of spawning, and histological analysis of the gonads of individuals in which spawning and mouthbrooding was previously observed. S. osphromenoides is considered a rare exception among labyrinth fishes (Osphronemidae family) because of the presumed maternal parental care, which is not found in other species of this family. According to our observations of 32 spawning events, parental care in this species was always performed by the male. Our visual observations were confirmed by video and histological analysis. This suggests that the sex in this species has probably been misidentified so far. We argue that the putative “females” (previously defined by external features) were in fact males, and that there are probably no exceptions to male parental care in osphronemid fishes.