I haven't heard specifically of seafood irritating a cat's tummy, but if he's sensitive to it, it makes sense. Ruby, as I think I've mentioned before, has a chicken intolerance, and any chicken at all in food will eventually start giving her, thankfully not terrible diarrhea, but definitely looser stools, and accidents around the house, and vomiting. So if you've made the correlation between seafood and Finn's tummy, I'd probably cut back on it, and see if that helps. It might be that he can't tolerate seafood at all, and you have to stop it altogether.when I feed food with seafood in it, I think it irritates his tummy. Anyone heard of this?