I tried to smoke a fish once - but couldn't keep it lit. (Sorry - that joke was just way
too obvious to pass up ....)
My experience has been that if you can eat it - you can smoke it. Perhaps with the exception of catfish - especially wild catfish, you really need to fry or "blacken" that to counteract the inherent muddy flavor.
Some of my favorites when we lived in Florida were barracuda, shark, pompano, swordfish, and red snapper.