Keeping mollies and guppies?

May 2, 2013
Hello, I currently have some guppies (male and female) growing in a small 10g tank and am in the process of setting up & cycling a 29g. I was hoping to get some male mollies to add to the 29g tank with the guppies (so that I don't have to deal with fry from both species). Will the male mollies bug my female guppies? Should I keep both genders of mollies if I am keeping both genders of guppies?
I've heard they can interbreed but that the fry usually turn out deformed or sterile... But I've also heard that this is pretty rare. So I just wanted to make sure I wasn't going to overwhelm my female guppies by having both male guppies as well as male mollies in the tank.
If anyone has experience keeping both, perhaps you can give me some insight! :)

So that this post isn't text only, I'll include a picture of my guppies that are starting to color up nicely! *twirlysmi

Feb 27, 2009
Although I've not kept livebearers in many years, from keeping mollies, guppies, swordtails and platies in the same aquarium, the males of each species would chase after and attempting to breed with the females of their own species.

But, if there were no females of their own species available (either because the tank had none or because other males outcompeted them), I often observed the males chasing and attemping to breed with the ANY female they could.