Gobys are pretty cool, I have a yellow watchman goby and he's fun to watch. My clowns never bothered him. My neon dotty back is pretty cool too, he can swim through some tiny holes in the live rock. The clowns went after him at first but he was able to escape with relative ease, so I know either one of those fish should be fine. Tangs are ok too but if I were you I'd get only one and a real small (maybe the size of your biggest clown.) They need a lot of swim room as they're expert swimmers, and if you get one make sure it isn't one that grows all that big, like a yellow or something.