Wash, clean and if necessary scale a good-sized fresh fish. Place in a shallow baking pan large enough to give the fish plenty of head and tail room. Spread over the fish the onion, carrots and lemon rind. Add lemon juice, vinegar, molasses, butter, bay leaves, salt, pepper and paprika. Sprinkle the bread crumbs on top. Pour in your favorite beer three-quarters covering the fish.
Bake about 40 minutes in a preheated 350° oven, or until well browned.
Place on a warm platter surrounded by pickled onions and mushrooms browned in butter. Cover with a sauce, if you wish, and decorate with parsley.
A 3-pound fish should serve 4-6 people.