Anyone ever heard of One Sided Livebearers? They sound funky. Apparently you have to have a "right sided" male and a "left sided" female for them to successively breed.
I haven't got pictures cause I don't own any but apparently there is a species of livebearer where males and females can only be one sided. AKA, a male that can only move his Gonopodium to the right needs a female who's birthing tube is on the left so he can successfully mate with her