Trinidadian guppies of the female persuasion would rather die than put up with males seeking a little sexual satisfaction. The guppies will travel into dangerous waters in order to keep out of the clutches of the pushy males.
Scientists have observed females of different species distancing themselves from pushy males but they disagree on why that happens.
Female guppies are more vulnerable to being attacked because of their size yet they will abandon feeding grounds if they have to deal with sexual harassment by male guppies.
Other theories offer up the females leaving to provide the best food for males or that the two sexes digest differently.
Safi Darden and Darren Croft, researchers at Bangor University in Wales, studied the sexual harassment angle.
"In nature, as a result of sexual conflict, females often experience harassment from males, which can be costly" for the females, they note.
Using 240 wild guppies (120 large females, 60 small females, 60 males)in a Trinadadian river they created four zones with various degrees of danger from predators.
"In the presence of males, females actively select areas of high predation risk but low male presence, and thus trade off increased risk against reduced sexual harassment," they concluded.
When the males were taken out of the scene the females returned to safer territory.
The study is in the British Royal Society's Biology Letters.