Get a royal gamma, or chalk bass... Although the bass is kinda the same colour as your chromis. Another good one would be a flame hawkfish.
As the other user suggested if you have a mesh lid you could put some wrasse in like a yellow canary or red high fin wrasse....
Here is an example of a mesh cover.. Lowes sells the aluminum parts in a package for window screening, Canadian tire sells the synthetic mesh for bird fencing. In total it would cost you $35 to build a lid. Light and easy to remove.
http://www.reefcentral.com/forums/sh....php?t=2078554