Check out some of the fairy or flasher wrasses. You can get a male and some females for a harem. It can be hard to get females sometimes.
Also, some of the cardinals make good schools. The Pajama Cardinal fish would work with three to five fish.
Question....why do you want a school of fish?
I did have a school of chromis in my 120g who one by one killed each other. I still have three left by themselves in my 29 QT and they do much better. However, my original reason was to use them as dither fish. IMO
it didn't really work. Now I have all one of each kind of fish with two clowns, and they all swim around quite well.
After looking at all of the many types of fish, I have yet to see a type of fish that I would want so many. In freshwater, there are many fish that school great in an aquarium. In SW
, there doesn't seem to be many.