Billfish are pelagic and migratory. They are found in all oceans, although they usually inhabit tropical and subtropical waters, swordfish are found in temperate waters as well. Billfish use long spears or upper jaw or beak swordlike to slash and stun prey during feeding. Bills they can also be used to spear prey, and have been known to ship spear (perhaps intentionally), but they usually are not used in that way. They are highly valued as a gamefish by sport fishermen.
The term refers to fish of the billfish family and Istiophoridae Xiphiidae. Big fish are "marked by the extension of the upper jaw, lower jaw further into the flat and long rostrum swordlike (swordfish) or round and spearlike (sailfishes, spearfishes and marlins).There are 12 species of billfishes right, are divided into two families and five genera. One family, Xiphiidae, contains only one species, the swordfish Xiphias gladius, and other families, Istiophoridae contains 11 species in four genera, including marlin, sailfish and spearfish.
There is controversy over whether the Indo-Pacific blue marlin, Makaira mazara, is the same species as the Atlantic blue marlin, Makaira nigricans. The following FishBase Nakamura (1985) in recognizing Makaira mazara as a distinct species, "primarily because of differences in the pattern of the lateral line system
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