Use glass pan about 6 x 10 inches. Melt a tablespoon or two of butter in pan, 1 to 2 minutes. Cut a block of thawed cod or haddock in 3 to 4 serving pieces. Mix 1/2 cup chopped onion and 1/2 cup chopped celery and arrange in pan so a pile is under each piece of fish. Pour 1/4 cup of orange juice into a small plate and pour seasoned bread crumbs onto a piece of wax paper. Dip fish pieces in orange juice and then in crumbs. Arrange fish on top of vegetables, cover with vented saran wrap and bake on high 5 minutes, turn the dish, and bake another 4 minutes.