What is a blue marlin?

The marlin is a large game fish. It has an elongated body up to 2.5 m long, a spearlike snout, and a long rigid dorsal fin which extends forwards to form a crest. Marlin are fast swimmers, occurring in all seas and hunting small and large fish. The larger species include the Atlantic blue marlin, Makaira nigricans, which have been reliably recorded in excess of 5.0 m in length and 1,800 lb (820 kg) in weight, and black marlin, Makaira indica, which have been reliably recorded in excess of 5.0 m in length and 1,470 lb (670 kg) in weight. They are popular sporting fishes in certain tropical areas and are also commercially important as a food fish. A marlin is a primary character in Ernest Hemingway's The Old Man and the Sea. Marlin are rarely table fare. Most modern sport fisherman release marlin after unhooking. 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 Fishes books.