In the daytime everything gets along fine, but at night polys (polies?, pollies? this spelling never really made since) really go to town on small fish. As far as water goes think you're fine but the only smaller fish that are gonna last in there long-term are the SRC, the pleco, and maybe congo tetras (they get to like 6 inches and are pretty fast). I'd actually be a bit cautious with the SRC, for the poly;s sake. A 13 inch senegalus tried to eat my 2 inch SRC, and it died a couple days after I took them both out of the water and removed the cat from its throat. How big is it? Once it's about 5 inches (they're pretty girthy) no poly would even try to eat it.