Uhm, cats eat fish with bones and scales too. They might choke on the bones sometimes, but it's pretty common to see stray cats chowin' on fishies they caught in shallow pools.
My cat does, of course I was told by my vet tuna is bad for them. my cats favorite foods are tomatoes, raw potatoes, and cucumbers and especially peanuts. He will get pieces of them once in awhile for a treat.