Line the broiler pan with heavy duty aluminum foil for easy cleaning. Preheat the broiler with the pan in place for at least 10 minutes. Generously coat both sides of fish fillets with the melted butter and place on broiler pan. If there is skin on the fish, the skin side is up. Broil about 3 to 4 inches from the heat source, and adapt the cooking time to the thickness of the fillets, -10 minutes per inch of thickness. If you have 1/4 inch thick fillets, total cooking time is about 2 and 1/2 minutes. If the fillets are 1/2 inch thick, the total cooking time is 5 minutes. You need not turn fillets of this thickness. Serve with lemon wedges and the side dish of your choice.