If you have seen some stuff like this, as I have:
In 2013, a study released in Nature, titled Bisexuality boosts attractiveness:
Female fish find some males more attractive if they have seen the males engaging in mating behaviour, even when such behaviour was with other males.
David Bierbach and his colleagues at the University of Frankfurt in Germany assessed the preferences of female Atlantic mollies (Poecilia mexicana) for various males of the same species (pictured) by showing them video animations of the males and measuring the time they spent in proximity to the images. Females preferred colourful males at first, but showed an increased preference for drabber males that they witnessed engaging in either homosexual or heterosexual mating behaviour. Another experiment confirmed that the females could tell the difference between male and female fish in the animations.
The authors suggest that this increased female preference for sexually active males may explain the prevalence of bisexuality in some group-living species. Homosexual behaviour, they say, confers a reproductive advantage on males of those species by increasing their likelihood of future heterosexual mating.