I swear this sounds like the setup for the kind of 50s B sci-fi movie that would have found a home on Mystery Science Theater 3000. Or possibly a SyFy Original Movie.

Of course, in the real world, the tuna are less likely to grow wings and fly around the beach, killing surfers and bikini-clad sunbathers before they make their way inland, knocking down the Hollywood sign on their way to the intense battle with the US Army in and around Downtown Los Angeles.