It is important to avoid eating cheese with fish because a fish's body is acidic, which is why the two do not mix. That is not to say you cannot have seafood with cheese. It is possible, but the cheese will need to be cooked before you add it to the fish. There are many types of fish that you can eat with cheese. It is important to know what kind of fish you are wanting to eat before you begin to break the rules. There are certain fish you should not consume with cheese, such as salmon, trout, catfish, etc.