Tuna or salmon in a baked potato casserole? Can I say *yuck*? Eeww. That's just nasty. I can't even imagine why anyone would possibly want to do that.
I'm with Pippinwhite on this one. Using the actual potato skins in the casserole is a new one on me. Not very appetizing, I don't think, especially if the skins weren't scrubbed well before baking. It would be awful to get a mouthful of grit. That would just ruin the whole dish. Using stew meat and brown gravy would probably be good, but then that kind of turns it into shepherd's pie or something similar.