Swordfish (Xiphias gladius) are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood. They reach a maximum size of 177 in. (455 cm) and 1,400 lb (650kg). The International Game Fish Association's all-tackle angling record for a swordfish was a 1,182 lb (536.15 kg) specimen taken off Chile in 1953.
The swordfish is named after its sharp bill, resembling a sword (Latin gladius), which together with its streamlined physique allows it to cut through the water with great ease and agility. Contrary to belief the "sword" is not used to spear, but instead may be used to slash at its prey in order to injure the prey animal, to make for an easier catch. Mainly the swordfish relies on its great speed and agility in the water to catch its prey. One possible defensive use for the sword-like bill is for protection from its few natural predators. The shortfin mako shark is one of the rare sea creatures big enough and fast enough to chase down and kill an adult swordfish, but they don't always win. Sometimes in the struggle with a shark a swordfish can kill it by ramming it in the gills or belly.
Females grow larger than males, with males over 300 lb (135 kg) being rare. Females mature at 4-5 years of age in northwest Pacific while males mature first at about 3 to 4 years. In the North Pacific, batch spawning occurs in water warmer than 24 °C from March to July and year round in the equatorial Pacific. Adult swordfish forage includes pelagic fish including small tuna, dorado, barracuda, flying fish, mackerel, as well as benthic species of hake and rockfish. Squid are important when available. Swordfish are thought to have few predators as adults although juveniles are vulnerable to predation by large pelagic fish.