Sailfish: Characteristics, Speed and Hunting

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Sailfish (Scientific name: Istiophorus platypterus) are the world' fastest swimmers. The can swim for short bursts at a top speed of 103 kilometers per hour (65 miles per hour). According to the Guinness Book of Records, one specimen was measured traveling 110 kilometers per hour (68 miles per hour), which is about the same speed as a cheetah.

Sailfish have a streamlined body. They can reach lengths of two to three meters (six to ten feet) and are named after their dotted dorsal fin, which can be raised or lowered into a deep groove running along its back. The fins is lowered when traveling at high speeds. Their bill is razor sharp. As part of their mating ritual they also jump out of the water a dozen or so times in succession.

Sailfish are a popular sport fish. They are often caught using a technique in which mullets are trolled without hooks and as the sailfish slap the mullet with their bills near the boat, fishermen cast flies as if they were going after trout. Fishing guides can often locate feeding sailfish by large masses of diving birds. Humans are the main predators of sailfish. Sailfish hooked by longlines have been attacked by great white sharks and killer whales. Predation of free-swimming sailfish is very rare.

Sailfish are not endangered. They are designated as a species of least concern on the International Union for Conservation of Nature (IUCN) Red List and have no special status according to the Convention on International Trade in Endangered Species (CITES). Indo-Pacific sailfish are frequently taken as bycatch by commercial tuna longliners in the Indian Ocean. They are also caught by gillnets, trolling, and harpooning by local fishers. In 2011, an estimated 28,800 metric tons of Indo-Pacific sailfish were caught within the Indian Ocean. Sometimes their meat ends up in sashimi and sushi in Japan. [Source: Daniel Duong, Animal Diversity Web (ADW)]

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase ; Encyclopedia of Life ; Smithsonian Oceans Portal

Sailfish Species

20120521-Florida_Sailfish.jpgSailfish live primarily in subtropical waters, The Atlantic sailfish (Istiophorus albicans) averages 11 to 22 kilograms (25 to 50) pounds and can reach 55 kilograms (120 pounds) and is found primarily in the Caribbean and along the east coast of the United States. The Indo-Pacific sailfish (Pacific sailfish) reaches 100 kilograms (220 pounds) and is found along the Pacific coast from California to South America. The largest can measure two and half meters (10 feet) from the tip of their bill to the tip of their tail.

The Indo-Pacific sailfish can be distinguished from other billfish by the twenty or bars on the sides of their body that are made up of bright blue spots. They have an estimated maximum lifespan of 13 to 15 years; however, the average age of catch and release specimens is 4 to five years. [Source: Daniel Duong, Animal Diversity Web (ADW)]

Although two sailfish species have been recognized.. No differences between them have been found in mtDNA, morphometrics or meristics and most authorities now only recognize a single species, Istiophorus platypterus. FishBase continues to recognize two species: [Source: Wikipedia]


Billfish bills are elongated upper jaws. The are use them to harpoon and batter prey and likely wield them against predators such as sharks. Billfish such as swordfish, sailfish and marlin have the ability to regurgitate their stomachs and reswallow them without suffering any ill effects. They do this to rid themselves of spines, beaks, bones and teeth of the prey they consume.

Even though large billfish are often called bulls, they are usually females. Females are considerably larger than males. Some species have long bills relative to their bodies weeks after they are born. Swordfish don’t begin developing their bills until they are a couple of feet long.

Swordfish, sailfish and marlin are often snagged on long lines, fishing lines that may stretch more than 50 miles and contain three or four thousand hooks. About 68 tons of sailfish were intentionally hooked on Atlantic longlines in 1996. As a result of this there numbers have sharply declined in recent decades.

There have been some reports of marlin, swordfish and other billfish ramming and attacking small boats, including ones with copper-sheathed hulls — and sinking them. One Dutch explorer wrote in his log in 1618, "there was such a noise...knowing not what meant." Back in port "we found a Horne sticking in the Ship, much like for thickness...a common Elephants tooth" and it “penetrated three planks and turned upward."

Hydrodynamic Billfish

Billfish have hydrodynamically-shaped bodies that allow them to swim very fast. Their snouts are pointed like a supersonic plane; their rear part tapers gently; and they have a crescent-shaped tail. The surface of their eyes are contoured so they don’t bulge and interrupt the streamlined surface.

source: PBS

The crescent-shaped tail of tuna, marlins, swordfish and sailfish, creates a thrust similar to that of the wings of birds. When swimming at high speeds, the fins of billfish slot into special grooves so the flow of water is not obstructed.

Marlin and sailfish hunt at such high velocities their cold-blood senses struggle to keep up. In responses they have evolved heaters in their brains and eyes, allowing them to perceive prey

Swimming at great speeds requires a great deal of energy and oxygen. Billfish obtain their oxygen by swimming with their mouth's open, forcing jets of water over their large gills. This means they have to swim continuously at relatively high speeds to breath.

Sailfish Habitat and Where They Are Found

Sailfish live in temperate, tropical, saltwater and marine environments and are found in coastal areas and in the open ocean far from land. They are typically found at depths of zero to 350 meters (1150 feet) at an average depth of 10 meters (33 feet). [Source: Daniel Duong, Animal Diversity Web (ADW) /=]

Sailfish are generally found in tropical areas and are particularly numerous abundant near the equatorial regions of the

sailfish range

Atlantic, Pacific, and Indian Oceans. Larger adults tend to inhabit the easternmost regions of the Atlantic and Pacific oceans. Indo-Pacific sailfish are distributed from 45° to 50° N in the western North Pacific and from 35° to 40° N in the eastern North Pacific to approximately 35° S in the eastern South Pacific. In the western Indian Ocean they live as far south as 45̊ S; in the eastern Indian Ocean they live as far south as 5° S. /=\

Sailfish are mostly found in coastal regions but can also be found in the middle of the ocean. Indo-Pacific sailfish spend most of their adult life between the mixed layer near the surface and the thermocline, occasionally diving into deeper waters where temperatures may reach as low as 8°C (46̊ F). Their preferred water temperatures though range between 25° to 30°C (77̊ to 86̊ F). Indo-Pacific sailfish migrate annually to higher latitudes during summer and migrate towards the equator in autumn.

Sailfish Physical Characteristics

Sailfish have fusiform body that is long, compressed, and remarkably streamlined. They are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them) and are normally dull in color but often have iridescent silverily blue stripes produced by pigment cells called melanophores that come to life when they hunt. Kirstem Fritches of the University of Queensland told National Geographic, “During stress or excitement, the cells contract their pigment to expose gorgeous metallic color in the skin below.” The colors are believed to be a warning to sailfish to keep their distance or perhaps to confuse prey.

Indo-Pacific sailfish range in weight from 50 to 100 kilograms (110.13 to 220.26 pounds), with their average weight being 70 kilograms (154.19 pounds). They range in length from 130 to 162 centimeters (51.18 to 63.78 inches), with their average length being 140 centimeters (55.12 inches). The largest specimens have measured up to 3.4 imeters, weighing as much as 100 kilograms (220 pounds. Their basal metabolic rate ranges from 250,000 to 1,500,000 cubic centimeters of oxygen per gram per hour, with their average basal metabolic rate being 525,000 cubic centimeters of oxygen per gram per hour. Sexual dimorphism (differences between males and females) is not pronounced: Both sexes are roughly equal in size and look similar. [Source: Daniel Duong, Animal Diversity Web (ADW) /=]

sailfish swimming fast with fins retracted

According to Animal Diversity Web: Indo-Pacific sailfish are dark blue dorsally, with a mix of brown and light blue laterally, and a silver-white color on their ventral side. This coloration is a form of obliterative countershading. This species is easily distinguished from other billfish by the approximately 20 stripes of light blue dots present along their lateral sides. Their head bears a long bill and jaws filled with file-like teeth. Their massive first dorsal fin is sail-like, with 42 to 49 rays, with a much smaller second dorsal fin, with six to seven rays. The pectoral fins are long, stiff, and falcate in shape, bearing 18 to 20 rays. Pelvic fins are thoracic in position and up to 10 centimeters in length. Scale size decreases with maturity and scales are nearly absent in adults.

Sailfish — the World’s Fastest Fish?

Sailfish are exceptionally strong and fast swimmers, able to reach speeds for short bursts up to 110 kilometers per hour (68 mph). Their streamlined body has an extraordinarily minute drag coefficient range of 0.0075 to 0.0091. After attaining the cruising speeds of 11 kilometers per hour (7 mph), they can fold down their first dorsal fin to reduce drag. Sailfish been observed at cruising speeds with their dorsal fins folded back halfway in pursuit of prey. When sailfish attack a school of fish, they fold their fin back completely, achieving attack speeds of up to 110 kilometers per hour, it is said.

I tried to find out how the 110 kilometers per hour (68 mph) figure was derived but couldn't come up with anything, According to Wikipedia, sailfish were previously estimated to reach maximum swimming speeds of 125 kilometers per hour (77 miles per hour), but research published in 2015 and 2016 indicate sailfish do not exceed speeds between 35–55 kilometers per hour (22-34 miles per hour). During predator–prey interactions, sailfish reached burst speeds of 25 kilometers per hour (15.5 miles per hour) and did not surpass 35 kilometers per hour (22 miles per hour). [Source: Wikipedia]

Ernest Hemingway with two sailfish he caught off Key West

World’s Fastest Fish according to the BBC
1) Black marlin — Maximum speed: 129 kilometers per hour (80 miles per hour)
2) Sailfish — Maximum speed: 110 kilometers per hour (68 miles per hour)
3) Striped marlin — Maximum speed: 80 kilometers per hour (50 miles per hour)
4) Wahoo — Maximum speed: 78 kilometers per hour (48 miles per hour)
5) Mako shark — Maximum speed: 74 kilometers per hour (46 miles per hour)
6) Atlantic bluefin tuna — Maximum speed: 70 kilometers per hour (43.5 miles per hour)
7) Blue shark — Maximum speed: 69 kilometers per hour (43 miles per hour)
8) Bonefish — Maximum speed: 64 kilometers per hour (40 miles per hour)
9) Swordfish — Maximum speed: 64 kilometers per hour (40 miles per hour)
10) Fourwing flying fish — Maximum speed: 56 kilometers per hour (25 miles per hour) [Source: BBC]

Sailfish Behavior, Perception and Communication

Sailfish are diurnal (active during the daytime), nocturnal (active at night), crepuscular (active at dawn and dusk), motile (move around as opposed to being stationary), migratory (make seasonal movements between regions, such as between breeding and wintering grounds), solitary and social (associates with others of its species; forms social groups). They do not appear to maintain a home range or territory. [Source: Daniel Duong, Animal Diversity Web (ADW) /=]

Sailfish are migratory and prefer to follow oceanic currents with surface seawater ranging in temperatures above 28°C (82̊C) . Indo-Pacific sailfish tagged with Pop-up Satellite Archival Tags have been monitored traveling over 3,600 kilometers to spawn or find food. Individuals sometimes swim in dense schools structured by size as juveniles and organize into small groups as adults. Occasionally, sailfish swim in a solitary manner. The fact that juveniles are often found feeding on the same prey suggests they feed in groups according to their size. /=\

Sailfish communicate with vision, touch and sound. They also use vibrations to communicate and sense using vision, touch, sounds, vibrations, magnetism and chemicals detected by smell.. Sailfish have been observed "flashing" their body colors via activity of their chromatophores, and utilize other visual signals (like dorsal fin movements) during breeding.

Their large eyes are flush to their head and are sensitive to low light conditions. A pair of nares are located in front of their eyes, Indo-Pacific sailfish use these nares to detect dissolved chemicals in the water column. Like other bony fish, sailfish has a lateral line used to sense movement and pressure changes in the environment and otoliths in their ear canals assist in detecting auditory stimuli. /=\

Sailfish Feeding and Hunting

sailfish with its dorsal fin extended and breaking the surface of the sea

Sailfish typically feed on epipelagic (open ocean) fish such as mackerels, sardines, and anchovies, as well as cephalopods. Sailfish hunt alone or in small groups, approaching their prey at high speeds. Once they reach their targets, they turn their bill quickly and hit the prey, stunning or killing it. In addition to hunting schools of small fish, they are also opportunistic feeders, occasionally preying on bottom-dwelling creatures. The species eaten sailfish depends on they prey that is available where they are. Remnants of cephalopod and fish mandibles found in their stomachs suggesting the rapid digestion of soft muscles. Charter boat captains locate feeding sailfish by looking for large masses of diving birds. [Source: Daniel Duong, Animal Diversity Web (ADW)]

Sailfish generally do catch fish by spearing them with their bills but rather by slapping them with their bills to stun them and then gobbling them up. Large groups often cooperate like wolves pursuing caribous to bring their prey under control, swatting, corralling them. Individuals take turns making rapid fire strikes. Reports of sailfish stabbing one another are rare. [Source: Paul Nicklen, National Geographic, September 2008]

Fishermen told Nakamura (1985); "when one or several sailfish found a school of prey fishes, they began to pursue it at about half speed with their fins half-folded back into the grooves. They then drove at the prey at full speed with their fins completely folded back and once they had caught up with it, they suddenly made sharp turns with their fins fully expanded to confront a part of the school and then hit the prey with the bill. Subsequently they ate the killed and stunned fish, usually head first." [Source: Jen Cork, Australia Museum, March 30, 2020]

Sailfish Feasting ion a Sardine Baitball

Describing sailfish on the hunt Jennifer Holland wrote in National Geographic, “Adorned for the hunt, with fin raised and changeable colors flashing, a sailfish in the Gulf of Mexico circles a ball of sardines, preparing to strike....More than a hundred sailfish keep tabs on an elephant-size school of sardines off Mexico’s Isla Mujeres. The big the prey up from deeper waters for easier feeding near the sunlit surface...Wielding its bony bill, the predator slices through a sardine school to isolate a smaller cluster — more controllable as the prey zigzag to elude capture. Sardines seek safety in numbers, moving as one.”

“Males and females alike circle the prey, pushing the school into tighter formation, and taking a few bites in turn. Each forward rush is punctuated by a startling flare of the dorsal fin, which more than doubles the hunter’s profile.”

Once the sardines are contained and in a position the sailfish want them to be, Holland wrote, “The predators shoot in from all sides, popping open fins and flashing iridescent colors as they get up close...Once a ball is under control, the sailfish take turns shooting through it, heads whipping side to side as they use their bills to bat sardines with remarkable precision. Pursuers then nab stunned fish before they can escape. Whittled down to it last bloody stragglers, the ball spins in a slow vortex, prey exhausted and no longer in perfect concert. Typically sailfish will consume every last one.”

Sailfish Mating, Reproduction and Offspring

Sailfish are oviparous (young are hatched from eggs) and iteroparous (offspring are produced in groups). They engage in year-round breeding and external reproduction in which sperm from the male fertilizes the female’s egg outside her body. Indo-Pacific sailfish breed three times a year: in the spring, summer, and fall in the thermocline layer. The number of offspring ranges from 800,000 to 1,600,000, with the average number of offspring being 1,200,000. The time to hatching ranges from 60 to 70 hours. As a broadcast spawners, sailfish are not involved in the raising of offspring. Females and males reach sexual maturity at age three to four. [Source: Daniel Duong, Animal Diversity Web (ADW) /=]

Sailfish are polygynandrous (promiscuous), with both males and females having multiple partners. According to Animal Diversity Web: Females extend their dorsal fin to attract potential mates. Males have been observed chasing females in a competitive manner, which ends with spawning for the winning male.

During the spawning season in the western Pacific Ocean, sailfish over 1.6 meters in length migrate southward from the East China Sea to Australia for spawning. Indo-Pacific sailfish off the coast of Mexico appear to follow the 28°C isotherm southward. In the Indian Ocean, there is a high correlation with the distribution of these fish and the months of the northeast monsoons when the waters reach ideal temperatures above 27°C.

Indo-Pacific sailfish spawn throughout the year in tropical and subtropical regions of the oceans, while their primary spawning season is during summer in higher latitudes. During this time, these fish can spawn multiple times. Female fecundity is estimated between 0.8 million to 1.6 million ova. During mating, a male and female pair up and swim together and release both their eggs and sperm into the water column.

Mature eggs are translucent and roughly 0.85 millimeters in diameter. The eggs contain a small globule of oil that provides nourishment for the developing embryo. Newly-spawned fertilized eggs average 1.30 millimeters in diameter. Although the larval growth rate is influenced by season, water conditions, and food availability, size of newly-hatched larvae generally averages 1.96 millimeters in notochord length, increasing to 2.8 millimeters after three days and up to 15.2 millimeters by 18 days.

Juveniles grow at an exponential rate during the first year, with females tending to grow faster than males and reaching sexual maturity sooner. After the first year, growth rate decreases. Indo-Pacific sailfish are estimated to reach adulthood at the length of 162 centimeters. Based on this size, it is inferred that individuals generally reach sexual maturity at the age of three to 4 years and continue to grow throughout their lifespan. /=\

Image Source: Wikimedia Commons, NOAA, streamlined sailfish from the Florida Museum

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023

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