Clean the fish. Split a thin fish down the back, and if you prefer, cut off the head and tail. Cut thick fish into slices and remove skin and bone. Oily fish need only salt and pepper, but dry fish should be spread with a little butter before broiling. Use double wire broiler and grease it. Put the thickest edge of the fish next to the middle of the broiler and broil the flesh side first. Cook about eight to twelve minutes, or until a delicate brown. Move the broiler up and down, that all parts may be equally browned, and then turn and cook the other side to crisp the skin. Broil over a clean fire, or if gas stove is used, one inch from gas in hot broiling oven. When done, the fish should be white and firm, and separate easily from the bone. Remove to a hot platter, flesh side up, first loosening fish from broiler Spread with salt, pepper and butter, and garnish with slices of lemon and parsley.