Marlin, Istiophoridae, also called Spearfish, are a family, of large marine fishes, of which several are popular in big-game fishing. They have an elongated body that in the larger species can exceed 4 m (13 ft) in length, a spear-like snout, and a long rigid dorsal fin, which extends forwards to form a crest. The common name is thought to derive from its notional resemblance to a sailor's marlinspike.[1] Marlin are known to be incredibly fast swimmers, reaching speeds in of about 80 km/h (50 mph).[2] The larger species include the Atlantic blue marlin, Makaira nigricans, which have been reliably recorded in excess of 2 m (7 ft) in length and 120 kg (250 lb) in weight, and the Black marlin, Makaira indica, which have been reliably recorded in excess of 5 m (16 ft) in length and 670 kg (1,470 lb) in weight. They are popular sporting fish in certain tropical areas.

Marlin are rarely table fare. Most modern sport fishermen release marlin after unhooking. However, the old fisherman in Ernest Hemingway's novella The Old Man and the Sea was storied to have caught an 18-foot marlin in order to sell its meat at market. Some marlin that are top record setting fish are taken and weighed on shore. Those records are most often recorded in the IGFA World Record Game Fish books.