Don't worry! CX F class offers a large selection of meals.
For supper, F has choices of appetizers, soups, salad, entrees, Asian selections, Vegetarian selections... There will always be one meat based entree choics... either beef or lamb (chicken... not so often) vegetarian options are always available as well. For midflight snacks, there is the hot pot rice, which will usually be meat based. Wonton, however, is shrimp based. For breakfast, it is less a problem -- mostly egg with meat dish... Chinese dim sum may involve some seafood dumpling or porridge.
Enjoy!
Carfield