Marlin vs Swordfish: 5 Key Differences

Whether you’re familiar with fish or not, you may be wondering what the differences are between marlin vs swordfish. Given how similar these two fish are, it’s no surprise that some confusion can arise! Both marlin and swordfish are from the same fish family, known as billfins. However, they are different fish, and there are ways that you can tell them apart.

In this article, we will compare and contrast marlin vs swordfish, including their physical differences and habits or patterns. By the time you finish reading, you should have a decent understanding of these differences and similarities. Let’s dive in and learn more about these fish now.

Comparing Marlin vs Swordfish

Marlin vs Swordfish
Black marlins are typically found in shallow water, and they are known to swim quickly to attack their prey with a fast slash of their bill.
Marlin Swordfish
Species Istiophoridae Xiphiidae
Lifespan 10-20 years 8-12 years
Habits Lives in deep, warm seas; experiences bursts of speed Migrates across deep seas as seasons change; often found at depths of over 300 meters
Size 7-12 feet, almost 2000 pounds 14 feet, over 1000 pounds
Appearance Streamlined body, long tail and nose Long nose and rounded body

The Main Differences Between Marlin vs Swordfish

marlin vs swordfish
Swordfish exhibit more migratory tendencies when compared to marlins, capable of traveling the seas as the seasons change and at great depths.

There are many key differences between marlin vs swordfish. These fish are members of different families, with marlins being members of the Istiophoridae family and swordfish belonging to the Xiphiidae family. Marlin fish tend to live longer than swordfish as well. Swordfish exhibit more migratory tendencies when compared to marlins, capable of traveling the seas as the seasons change and at great depths.

But this is only where their differences begin. Read on to learn about marlin vs swordfish in more detail now.

Marlin vs Swordfish: Species Classification

One of the main differences between marlin and swordfish lies in their species classification. Marlin are members of the Istiophoridae family, while swordfish are members of the Xiphiidae family. This may not seem like a very important distinction, but it is one key difference between these two fish. They are not technically related, even though they look very similar to one another.

While there are roughly 10 other species of fish belonging to the family that marlin are part of, swordfish are the one and only species found under the name Xiphiidae. While this fact won’t help you identify a wild marlin or swordfish, it can be a very interesting distinction between these two fish.

marlin vs swordfish
Marlin are members of the Istiophoridae family, while swordfish are members of the Xiphiidae family.

Marlin vs Swordfish: Appearance

Another key difference between marlin vs swordfish lies in their overall appearance. While these fish are strikingly similar upon first glance, there are many things that you can look at in order to tell them apart. Let’s go over some of those key differences now.

One of the main differences between marlin and swordfish is their overall coloring. Swordfish are typically only silver and gray in appearance, while marlin have a very distinct blue top to them. Their underbellies remain gray or silver, much like a swordfish. However, having a blue top fin and back makes it easy for the average person to tell a marlin and swordfish apart.

Swordfish also have a taller dorsal fin when compared to a marlin. Marlin dorsal fins are more streamlined along their back, which likely helps them reach speeds of over 50 miles per hour. Swordfish are also built thicker than marlin are, with marlin remaining a more slender fish overall despite them often growing bigger than swordfish.

marlin vs swordfish
Swordfish are typically only silver and gray in appearance, while marlin have a very distinct blue top to them.

Marlin vs Swordfish: Migratory Habits

Marlin and swordfish also differ from one another in their migration habits. Most marlin tend to spend their lives in one location, often at a deep depth in the sea. Swordfish are different from marlin in that they migrate annually across the sea, often swimming thousands of miles to reach their destination. This key behavior is just another way that you can tell them apart.

Marlin vs Swordfish: Size

Another difference between marlin vs swordfish is their size. While both of these fish are quite large, marlin tends to grow much larger than swordfish, often reaching close to 2,000 pounds while swordfish hover closer to 1,200 pounds at a maximum. Many swordfish that have been bred for commercial purposes only reach 200 pounds or less.

Given the large size that marlin can reach, they are known for pursuing and eating other large open sea fish such as tuna. In both of these fish species, the female fish tend to outgrow the male fish by a large margin.

marlin vs swordfish
Swordfish are different from marlin in that they migrate annually across the sea, often swimming thousands of miles to reach their destination.

Marlin vs Swordfish: Lifespan

A final difference between marlin vs swordfish lies in their life span. Marlin typically outlive swordfish, depending on the gender of the fish in the first place. Many marlin tend to live 10 to 20 years, especially if they’re female, while most swordfish live 10 years or less, depending on their gender.

Swordfish also have more issues than marlin in terms of their reproductive cycle. Most female swordfish lay their eggs between their fourth and fifth years of life, which often means that they never reached this point due to fishing and other potential predators. Most marlin species reach sexual maturity at 2 to 4 years of age.

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