What's A Good Watching Fish?

[intarsiabox]

I have a 90g reef with a foxface, 2 seabe clowns, 2 percs, a royal gramma and a yellowtail blue damsel in it. The royal gramma hides all day and the rest of the fish will only swim around one side of the tank in about 1 foot of space. This is leaving me with 3 feet of fishless tank. I am looking for a fish that is compatible with both my current fish and corals and likes to be an active swimmer. I've even tried feeding on the other side of the tank but only the blue damsel and my shrimp will make the trip across the tank for food. Any suggestions?