I have to say that I really don't feel that any fish is okay with seahorse. they are very sensitive and slow eaters as well. most fish are either too mean and the seahorse gets picked on to death or just too fast and the sea horse starves. they are also one of the most difficult species to keep.
That being said I have know people (that have been keeping seahorses for years) who have kept some of the more passive fish like bi color blenny, fire fish, dragonets, and just about any goby without much problems just make sure they are getting enough to eat. and as long as you understand that you might have to remove fish if there is a problem.
And please keep in mind when you decide on your coral that sea horse can be hurt by a lot of different kinds of coral.
If these are your first attempt at SW I would try something easier first if not then good luck.
