The spearfish is a streamlined, fast-swimming predatory fish belonging to the billfish family, which also includes marlin and sailfish. These oceanic hunters are classified under the genus Tetrapturus and share the common trait of an elongated, spear-like upper jaw. They are recognized across the world’s tropical and temperate oceans for their speed and sleek physique, and are considered the smallest and least-studied members of the billfish group.
Defining Physical Traits
Spearfish are distinguishable from their relatives by their smaller size and a noticeably shorter, thinner bill. This “spear” is less robust than the swordfish’s blade or the marlin’s spear, often barely exceeding the length of the lower jaw in some species. Their body is highly compressed laterally, giving them a slender, lightweight profile compared to other billfish.
The dorsal fin is long and high, extending along much of the back, though it does not reach the height of a sailfish’s sail. This first dorsal fin begins abruptly with a pronounced peak before leveling out. While some longbill spearfish can reach up to 2.4 meters in length, the average specimen measures between 50 and 70 inches and weighs 20 to 40 pounds. The maximum recorded weight for the largest species rarely exceeds 68 kilograms (150 pounds).
Types and Global Habitats
The genus Tetrapturus includes four species, each occupying distinct geographic ranges. The Shortbill Spearfish (T. angustirostris) inhabits the Indian and Pacific Oceans. Conversely, the Longbill Spearfish (T. pfluegeri) and the Roundscale Spearfish (T. georgii) are found predominantly in the Atlantic Ocean. The fourth species, the Mediterranean Spearfish (T. belone), is confined to the Mediterranean Sea.
All spearfish are highly pelagic, meaning they live in the open ocean, far from coastal shelf waters. They prefer the warmer surface layers of tropical and subtropical waters, showing a narrow thermal tolerance that limits their time in deeper, colder zones.
Diet, Behavior, and Conservation
Spearfish are active predators that feed near the surface, utilizing their speed and bill to secure prey. Their diet consists primarily of small schooling fishes, such as flying fish and sardines, along with squid and crustaceans. Like other billfish, they hunt by slashing their rostrum into schools of fish to stun or injure them before consuming them.
These fish are generally solitary, spending over 90% of their time in the top 100 meters of the water column. Their small body size provides less thermal inertia, limiting their ability to tolerate the cold temperatures of deep water compared to larger billfish.
Spearfish are pursued in recreational sport fishing, valued for their acrobatic fighting style and speed. They are also frequently caught unintentionally as bycatch in commercial longline fisheries targeting tuna and other billfish. Although the general conservation status is often listed as “Least Concern,” they remain the rarest and least-understood billfish, making certain populations vulnerable due to a lack of detailed data.