Help!

[MegTheFish]

Okay, here are the stats:
10 gallon glass aquaruim
Whisper 10 filter
50 watt heater
gravel, decorations, fake plants
Occupants:
2 female guppies, 3 male guppies, 1 female balloon molly, 1 flying fox

The larger of my 2 female guppies (who has a very large fin, you'd think she'd be a male!) has out of the blue, started attacking my other fish! She seems to bother the other female guppy the most, she literly lunges at her and tears her fins apart! I noticed this on all the other guppies (but not the fox or molly) but their damage on their fins wasn't as bad. I know it is her because I've seen her in action, and her fins aren't damaged at all, and if it was another fish they would go after her first because she has the longest fins.

Help?

P.S.-
I forgot to add some important information. I bought a the evil female and one other male about 3 weeks ago and added them to the tank. Before I added them, the occupants of the tank were: 2 male guppies, 1 female guppy, 1 female balloon molly, and 1 flying fox.

Edit: I edited out the gourami, since he just passed away

 

[simonbrown403]

strange, my wife use to keep and breed guppy, she had a small army in a 100ltr tank whith out any bother, its usuall the males that fight amonsed there selfs. ide sujest moving the battered female before it dies

 

[breezer40]

Is there any chance the offender could be a male? I breed these and to date have only had one male that has done this but that was because he was trying to mate with one of the girls.