Mexican guppies sexually harass other fish

NewScientist reports:

Male guppies may sexually harass females of another fish species to prevent them from reproducing, researchers suggest. They believe the guppies -- which have invaded Mexican rivers and lakes -- are using sex as a way of suppressing one native fish population. ...

Guppies, originally from Trinidad, invaded Mexican waters in the 1950s. ...

They put male and female guppies in aquariums with female skiffia and found that no matter how many female guppies were around, male guppies would try to copulate with females of both species.

Their advances were unsuccessful, but Valero and her colleagues believe that the attempts at sex might be harming the female skiffia. ...

The two species have very different ways of reproducing. Skiffia sex is consensual -- males have no extending reproductive organ so the only way for their sperm to reach the females' eggs is for the two animals to line up their genital openings.

Sexual harassment

Guppy sex is more violent. Males have a hooked genital organ known as a gonopodium, which they insert into the females.

The article goes on to say that American minks have been sexually harassing European minks.