Mollies and Swordtails don't breed together do they? I have a femaile Molly that acts like a little puppy, following my male Swordtail around the tank. She's not nipping or being aggressive, but will just swim either behind him or beside him. Sometimes she acts like she is showing off a little. Its kind of cute to watch...like she has a crush on him...lol.
Of course, he just ignores her and goes about his business.
Of course, he just ignores her and goes about his business.