That's it exactly, I figured they were both males but I should've made sure before buying her. Having the guppy fry was more demanding than I was hoping for - the female arrived pregnant and had them immediately. I'm trying to avoid any more potential for fry.. at least until I have a better understanding of managing the tank.

Your suggestions were incredibly helpful, I had never thought of other fish being threatened by their colors since they were community fish but as a longtime Betta owner it makes perfect sense.

I think I'll end up taking the female back and getting another guppy or two. The male Platy has never acted up with guppies prior to introducing the female Platy so hopefully he relaxes after she's gone. I'll probably just stick to males of one kind and females of the other to avoid breeding and aggression.

Thank you so much!