En garde! It’s not easy to see the differences between sailfish and swordfish at first glance. They’re both lightning quick and have bills that look like they’d pierce a dingy. But on closer inspection (just as we did in “8 Incredible Differences Between Manatees and Dugongs”), the differences begin to show.

Both are from the same Order, Perciformes, known colloquially as the billfish family. They are both large marine fish that are fundamental apex predators in their environments. Found in tropical and temperate waters throughout the world’s oceans, they generally live far from shore.

To understand their differences more deeply, we take a look at the main points that separate these creatures:

Sailfish

Scientific name: Istiophorus albicans

Diet: Tuna, mackerel, needlefish, jacks, sardines, anchovies

Lifespan: 4 years

Size: Up to 3 metres

Weight: Up to 90kg

Fast facts:

  • Fastest fish in the ocean
  • Can change colour instantly
  • Two species: Atlantic sailfish and Indo-Pacific sailfish

istiophorus_platypterus

Size

When it comes to size, swordfish have it bigger. Growing over four metres, they are one of the largest of the Order. Sailfish, by contrast, can grow up to three metres – but this is for an important reason…

Speed

Smaller, and built for speed, sailfish are the fastest fish in the ocean. Able to pierce through the ocean at pace, swimming 100 metres in just 4.8 seconds, they take gold in every sprint with a top speed of 110 km/h. Swordfish, come in a close second – with the ability to swim at up to 80 km/h.

Habitat

Swordfish are found worldwide in the Atlantic, Pacific and Indian Oceans. They reside in tropical, temperate, and sometimes cold waters at depths between 200 and 600 metres. Swordfish inhabit waters with the widest temperature range of any billfish (5–27°C) and migrate seasonally to warmer waters in winter and cooler waters in summer. Sailfish range throughout the warm and temperate regions of the world’s oceans, and prefer temperatures between 21°C and 28°C.

Atlantic sailfish feeding on sardines they have trapped against the surface. Caribbean Sea just outside Cancun, Mexico. © Shutterstock

Atlantic sailfish feeding on sardines they have trapped against the surface, Caribbean Sea just outside Cancún, Mexico © Shutterstock

Lifespan

Swordfish

Scientific name: Xiphias gladius

Diet: Squid, octopus, bluefish and mackerel

Lifespan: Up to 9 years

Size: Up to 4.55 metres

Weight: 500–650 kilograms

Fast facts:

  • Swordfish have special organs next to their eyes that keep their brain and eyes warm in cold water
  • They mostly feed at night
  • Their swords can slice their prey in half

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It’s a short and sweet life for the sailfish, which burns out almost as fast as it bursts through the water. At just four years, their maximum lifespan is less than half that of swordfish.

Fins

Sailfish get their name from the long dorsal fin that runs down most of the length of their body and resembles a sail. This fin is retractable and has been observed being used to create a wall when hunting in order to keep smaller fish from escaping. The dorsal fins on swordfish are rigid, fixed in an upright position and directed backwards.

Colours

Swordfish are dark above and whitish with a silvery sheen below, the upper surface varying from purplish to dull blue or even to black. Sailfish can change their body colour instantly, and they often do so when hunting, with the normally bluish-silver lateral sides darkening to almost black just before beginning an attack.