I am allergic to shrimp (and I assume all shellfish, crustaceans), but only if I actually eat some. What kind of allergy do you have? Mine is gastrointestinal so it won't kill me, but it makes me wish I could curl up and die for 7-8 hours. If yours is anaphylactic you definitely need to let them know ahead of time. At our local Japanese Steak house, all I do is tell the chef that I am allergic. If I tell them before they cook, they always cook the seafood last, including the shrimp appetizer. Otherwise I tell them while they're cooking so not to make everyone wait. I'm not so sensitive that food cooked together is a problem. A lot of restaurants fry foods in the same oil so anyplace that serves fried seafood usually cooks it in the same oil as the fries, chicken, etc, unless they state otherwise.