Wash the fish or the fish steaks in cold water, then pat thoroughly dry with paper towels.
Sprinkle the fish liberally with salt and pepper on both sides, put it on a large platter, and add the olive oil, lemon juice, and rosemary. Turn the fish two or three times to coat it well. Add the bread crumbs, turning the fish once or twice again until it has an even coating of oil-soaked bread crumbs. Marinate for 1 or 2 hours at room temperature, turning and basting the fish from time to time.
If using charcoal or wood, light the charcoal in time for it to form white ash before cooking, or the wood long enough in advance to reduce it to hot embers. If using an indoor gas or electric grill, preheat it at least 15 minutes before you are ready to cook.
Place the fish 4 to 5 inches from the source of heat. Do not discard its marinade. If cooking on charcoal or with wood, throw the bay leaves into the fire, otherwise omit. Grill on both sides until done, turning the fish once. Depending on the thickness of the fish steaks or the size of the whole fish, it may take between 5 and 15 minutes. While cooking, baste the top with the marinade. Serve piping hot from the grill.