Swordfish is the dense, meaty flesh of a giant open-ocean predator (Xiphias gladius) named for the long, flat, sword-like bill that extends from its upper jaw. Sold almost entirely as thick, pale, boneless steaks, it cooks more like a beefsteak than a delicate fillet — firm, mildly sweet and clean-flavoured — which has made it a grilling favourite from the Mediterranean to the coasts of the Pacific, though its size and place at the top of the food chain make it one of the higher-mercury fishes.