Fish lets others woo mate then muscles in

摘要

DOMINANT males in a species of Amazonian fish have a simple way to improve mating chances. They hide while smaller, less-dominant males work hard to persuade a female to lay eggs, then they steal the receptive female's attention. Lower-ranking male sailfin tetras (Crenuchus spilurus) may spend days circling aquatic weeds with their fins fully extended to woo a mate. Tiago da Silva Pires at the National Institute for Amazonian Research in Amazonas, Brazil, witnessed such displays in streams in the Amazon forest. Then he noticed that as soon as a male began leading a receptive female to a nesting area, a more dominant male emerged from hiding - and the female would mate with him instead. This has been dubbed "courtship piracy". To study this in more detail, da Silva Pires and his team collected fish and brought them to the lab, placing one large male, one small male and one female in each of 22 aquariums. In all cases, the larger male hid in a nesting pipe while the smaller male made "energetic" efforts to court the female. When the female signalled receptivity to spawning, the hard-working male would lead her to the nesting area, but in all cases in which spawning occurred -19 of the 22 - it was the dominant male who the female mated with (Animal Behaviour, doi.org/gp97).