Well if you want some ideas you can check my Sig. Although ive never had problems with small fish and bettas, provided the small fish aren't nippers.When I got my neons a few years back I added a betta, and I woke up to a fat betta and no neons,so,since cardinals are bigger fish are they safe with a betta? What about angel fish, are they safe with a betta or will the betta go for the fins? I'm setting up a new tank in a few weeks and am just throwing out some ideas. I plan on looking at fish from LiveAquaria.com, and thatfishplace.com just to see what I might like I'm planning on it being another planted tank, with driftwood.