Mix garlic salt or powder in vegetable oil. Cut fish nto 2 to 3 inch pieces and marinate in oil mixture for 2-4 hrs. in fridge. Remove fish from oil (let most of oil drip off) and place on cookie sheet. Put butter or margarine on each piece and cover each piece with parmesan cheese.
Bake in 350 degrees F. oven for 30-45 minutes until chees starts to brown. You may cook at higher heat (400-450 F) and get done quicker and cheese will be browner.