... I just like the contrast against the brighter reef colors and my SPS. Unfortunately I have black clowns, so they would probably look better against blue than black.
Krylon Fusion is a pretty solid paint, just throwing that on there.
Btw, If you go to Petco or Pet Supermarket you can buy the backrounds that you just tape onto the back of the tank. Its cheap and you get a black and a blue, so you can try out what color you like more.