Preheat oven to 350 degrees. Cut open a brown shopping bag to make a flat piece of paper. Rub just enough oil on the bag to coat. Place one fillet on the paper. Sprinkle with lemon juice, garlic powder and paprika to taste; top with 2 to 3 thin slices of butter. Place second fillet on top of first and repeat seasonings. Place lemon slices on top of fillets. Wrap the paper around the fillets. Place on a baking sheet. Bake 45 minutes.