In a recent Brief Communication in the Journal of Fish Biology, we describe previously undocumented male mating behaviors in Alfaro huberi, one of two species in the genus Alfaro. Although poeciliid fishes are classic models for sexual selection research, key aspects of behavior remain undescribed in many species.
Like its congener Alfaro cultratus, A. huberi males approach females from above, an unusual posture compared to most poeciliids. However, the specific display differs. Instead of rubbing the dorsal head surface with pelvic fins (as in A. cultratus), A. huberi males perform a distinctive “chin touching” behavior, repeatedly tapping or hooking the gonopodium under the female’s chin and sometimes lifting her upward in the water column. We also document a second behavior, “repositioning,” in which males push females upward from below. Although elements of this behavior have been observed by aquarists, this study provides the first formal description.