I'm glad you told me that. I'd hate to buy five and have them everywhere through the reef. It comes down to the age old problem I have always had, once I put a fish in the reef it is pretty much there for life..you know.
Eviota gobies do pretty much what the one pictured is doing. They sit on the rockwork a lot, only occasionally sculling in the water to catch a piece of food. If you've ever kept neon gobies their behavior is fairly similar. You can keep them in groups but I doubt anyone would describe it as a "school".
I think some Ptereleotris gobies would be your best bet. Do you have a bit of fine sand at the bottom of your tank?