Many fish and shellfish benefit from a quick soak in a marinade to boost flavor and help retain moisture. Even so, use care when choosing marinade ingredients and limit the seafood's time in the marinade so as not to overwhelm its natural flavor. Usually half an hour is enough time to add flavor to a delicate piece of seafood: less time is needed if you are using a strong acid in the marinade, such as lemon juice, which chemically "cooks" the food and alters its texture.
Microwave ovens work by shaking up the water and fat in food, which in turn, makes heat. Covering food with microwave-safe plastic wrap or putting it in a microwave-safe, covered casserole dish locks in steam. The combination of inside heating and outside steaming cooks items in less time than it would take otherwise.