Sailfish vs Swordfish: Five Main Differences Explained

Written by AZ Animals Staff
Published: August 9, 2021
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The sailfish and the swordfish are both examples of billfish, or fish with beaks that have been elongated to resemble spears or lances. To a casual observer, the swordfish and sailfish look alike, and both are prized as game fish and make good eating. Females of both species produce millions of eggs at spawning time. Yet there are notable differences. For one thing, the two fish belong to different families and aren’t as closely related as some might suppose. The swordfish belongs to the Xiphiidae family and is its only member. The sailfish is part of the Istiophoridae family and is related to marlins and spearfish. Read on to discover other differences between these two magnificent animals.

Comparing Sailfish vs. Swordfish

Here’s a table that can help show the differences between a sailfish and a swordfish.

Sailfish Swordfish
Length 9.8 to 10.9 feet 10 to 15 feet
Weight 200 pounds or less Over 1000 pounds
Speed 68 miles per hour 60 miles per hour
Sail Yes No
Species One Maybe two
Teeth Yes Teeth lost by adulthood
Lifespan 13 to 15 years As long as 16 years
Sexual dimorphism Sexes alike Females larger than males
Pelvic Yes No

The Five Key Differences Between Sailfish vs Swordfish

1. Sailfish vs Swordfish: Body Type

Interestingly, the sailfish isn’t that much shorter in length than the swordfish but tends to weigh much less. Sailfish rarely weigh over 200 pounds, though the heaviest swordfish caught weighed close to 1200 pounds. Both fish are compressed, torpedo-shaped and two of the fastest swimmers in the ocean. However, the swordfish lacks the sailfish’s trademark sail, which is just a long, retractable dorsal fin that stretches most of the length of the animal’s back.

The swordfish’s first dorsal fin is near the head, large and curved, while the second is much smaller and near the stem of the tail. The first pair of pectoral fins are about as long as the first dorsal fin. The fish has no pelvic fin but a keel on the stem of the tail. The tail fin is shaped like a half-moon and has very long lobes. Adults lack scales and teeth.

Unlike the swordfish, sailfish have teeth, scales, and very long pelvic fins shaped like rods, though scales may be missing in older adults. When the fish wants to go fast, it depresses its dorsal sail into a groove in its back. As for the sail itself, it has 42 to 49 rays, and its middle rays are longer than the depth of the fish’s body. The sailfish also has a much smaller second dorsal fin.

There are two keels in the root of the tail, and like the swordfish, the tail is half-moon-shaped with long lobes. The fish also seems to be left or right “handed” when it comes to using its bill. Some fish slash toward the left and some toward the right, and this appears to be advantageous when the sailfish hunts in a large group.

The bill of the sailfish is round and comes to a point, while the bill of the swordfish is flat.

2. Sailfish vs Swordfish: Habitat

Though swordfish and sailfish are both found in warm waters of the Indian, Pacific, and Atlantic Oceans, swordfish has a somewhat larger range and can swim in colder waters. They can swim in waters as cold as 41 degrees Fahrenheit and have an organ near their eyes to keep their brain and eyes warm in such chilly water.

3. Sailfish vs Swordfish: Group

Swordfish tend to be solitary, and when they swim together they make sure to keep a wide distance apart. Sailfish are more likely to swim in schools. When the fish is young, the schools are arranged according to the size of the fish. Adults swim in smaller groups. Their slashing bills injure their prey, which makes it easier for members of the hunting party to catch and eat them.

4. Sailfish vs Swordfish: Coloration and Chromatophores

Sailfish are dark blue on the top and silvery below, and adult sailfish have vertical rows of golden spots on their sides. They have chromatophores in their skin, which allows them to change or flash their colors to an extent. They do this mostly during the breeding season. Females also expand their sail fins to attract males.

Swordfish are gray, brown, or black above and gray or sometimes yellowish below.

5. Sailfish vs Swordfish: Name

Swordfish and sailfish not only do not belong to the same species, but they also don’t belong to the same genus or even family. The Indian sailfish’s scientific name is Istiophorus platypterus. Istiophorus is from the Greek words istios, which means “sail,” and pherein to “carry.” Platypterus means “flat or broad wing or feather.” The other subspecies of sailfish, the Atlantic sailfish, is Istiophorus albicans. The epithet here is Latin for “white.”

The swordfish has the scientific name Xiphias gladius. Xiphias is from the Greek word for “sword,” and gladius is from the Latin word for “sword.”

Next Up: How Do Whales Die? 7 Common Causes of Death for Whales

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About the Author

AZ Animals is a growing team of animals experts, researchers, farmers, conservationists, writers, editors, and -- of course -- pet owners who have come together to help you better understand the animal kingdom and how we interact.

FAQs (Frequently Asked Questions) 

What's the difference between a Sailfish vs Swordfish?

The main difference between a sailfish and a swordfish is that the first dorsal fin of the sailfish is huge and forms a type of sail down the animal’s back. Not only that, it can be folded away as the sailfish swims. The raised sail is believed to keep the fish’s head steady when it hunts. Though a sailfish is only a little shorter than a swordfish, a swordfish can weigh over five times as much. Sailfish swim in groups, or schools while swordfish tend to be solitary. Sailfish have pelvic fins and keep their teeth, but swordfish do not have pelvic fins and lose their teeth and their scales by the time they’re adults.