Mine are both females and they honestly NEVER looked at the screen, even when the other was on the other side. It was like they could care less. IT's really funny because the fish on the other side (not pictured) ended up being such a bully that I yanked her from my sorority and sent her to live in exile with Aunt Sara. And she never once seemed to notice the cambodian on the other side of the screen.
It was just plain plastic mesh from our craft store. I washed it well (without soap) first. There were two choices and this was the more open one. The other craft mesh had much smaller holes and it was very hard to look through it.