I had a lone platy in a 10 gallon tank for over 6 months with some cherry barbs. I can't remember how long it's been since I had more than the one platy. About a 5 or 6 weeks ago I moved the platy and barbs to my 50G. Today while doing a water change I noticed 3 half inch long platys. This really surprised me.
I know I kept a journal on my Barb tank, mainly to track maintence and water changes. I will have to check it. I can't access it right now b/c my files are saved to an external hard drive that is not hooked up to my desktop; my wife is fixing it for me and doing a clean install.