Billfish of the family Istiophoridae — large, fast-swimming marine predators — are marketed as marlins. Commercially significant species are black marlin (Makaira indica), blue marlin (M. nigricans) and striped marlin (Tetrapturus audax). Their firm, meaty flesh suits steaks and sashimi; they are sold fresh, frozen and occasionally smoked, and in Japan also go into fish sausages. As long-lived apex predators they accumulate mercury, prompting consumption advisories from food-safety authorities — especially for pregnant women and children — while imports are checked against regulatory limits for mercury and histamine, and stock-management measures constrain catches.