Heat oven to 350F. Make white sauce with the 2 tbsps.
butter, flour, milk, and seasonings. Add cheese, stirring
until melted. Cook fish; skin, bone, and cut in pieces.
Add fish, shrimp, lobster, and sherry to sauce; pour
into 2 quart casserole. Toss crumbs with the 3 tbsps. of
butter; sprinkle on top of casserole. Bake at 350 degrees
F, for 25 minutes. Serves 6-8.