Place halibut fillets in a shallow baking dish. In a small bowl, combine melted butter, lemon juice, parsley flakes, oregano leaves and garlic powder. Pour over the halibut fillets and let marinate for 15 minutes.
Preheat grill to medium-high heat. Place the halibut fillets on the grill and cook for 8 minutes per side or until cooked through.
Serve with your favorite sides and top with remaining butter sauce.