Marlin vs. Swordfish: What’s the Difference?

Marlin vs Swordfish

Marlins are fast swimmers and have long bodies and sword-like bills — and so do swordfish. Now, this begs one of the most asked questions, “Is a marlin a swordfish?”

A marlin is different from a swordfish. Although they look similar, marlins and swordfish are distinct species from different taxonomical families. These fishes also have differences in terms of their physical appearance, behavior, diet, taste, and lifespan.

In this guide, we’ll dive deeper into the distinct characteristics and aspects that set marlins apart from swordfish. We also included photos and videos to help you easily differentiate the two. So, let’s start! 

Summary of Marlin vs. Swordfish

Species:Istiophoridae familyXiphias gladius
Appearance:Swordfish have a broad, flat bill, and their dorsal fin resembles the dorsal fin of a shark. Swordfish lack scales and teeth.Swordfish have a broad, flat bill, and their dorsal fin resembles the dorsal fin of a shark. They lack scales and teeth.
Size:Up to 16 feet10–14 feet
Weight:100–1,900 pounds, depending on the speciesUp to 1,400 pounds
Speed:50–80 mph, depending on the speciesUp to 60 mph
Habitat:They thrive in open oceans and prefer temperate and tropical seas.They reside in open oceans and are found from the surface to depths of over 600 meters.
Distribution:Marlins are found in the Atlantic, Pacific, and Indian Oceans.Swordfish are distributed worldwide in both tropical and temperate seas.
Diet:Their primary diet consists of squid, small fish, mackerel, and tuna.Their diet primarily includes squid, fish, and crustaceans.
Lifespan:10–15 yearsUp to 9 years
Taste:Marlins have a firm and lean meat with a more pronounced flavor.The meat of the swordfish is firm, dense, and moist, with a slightly sweet and mild flavor. It’s less fishy compared to marlin meat.

Understanding Marlins and Swordfish

Marlins and swordfish come from the same taxonomical suborder, Xiphioidei, known to include species categorized as billfish. This is why it is no surprise that these fishes look similar and are often confused.

What Is a Marlin?

Marlin swimming with sea lions

Marlins, belonging to the family Istiophoridae, are a group of oceanic fish known for their long bills and knack for speed. These fish are apex predators, meaning they’re at the top of their food chain.

These fish are found in the Atlantic, Pacific, and Indian Oceans. Each species of marlin has adapted to its unique habitat, sporting deep blue to silvery bodies that slice through water with ease.

Among the species, the blue marlin (Makaira nigricans) stands out for its size, with the females growing larger than the males, sometimes weighing over a thousand pounds.

The black marlin (Istiompax indica) is known for its power, having a stiff dorsal fin, and can reach similar sizes to blue marlins.

Then there’s the striped marlin (Kajikia audax), with its signature stripes and a sleeker build, and the white marlin (Kajikia albida), the smaller, more slender member of the family, valued for its fighting spirit when caught.

Marlins have a carnivorous diet, preying on squid and pelagic fish, which they stun with their sharp bills. These solitary swimmers also migrate across vast ocean distances, guided by warm currents.

What Is a Swordfish?

Swordfish leaping from the water

The swordfish, scientifically named Xiphias gladius, stands out in the ocean for its elongated, flat bill, which it uses like a sword.

This solitary species is the only member of its family, Xiphiidae. Adult swordfish have no scales or teeth, but their dorsal fin is distinctive, resembling sharks.

Swordfish prefer warmer, near-surface waters but can dive deep to hunt. These creatures can grow up to 14 feet and have been known to reach weights up to 1,400 pounds.

They’re powerful swimmers — their streamlined bodies are designed to cut through water with minimal resistance.

Swordfish are nighttime hunters, diving into the depths to feed on fish and squid. Their sharp bills play a crucial role in stunning their prey, making them effective predators.

They are a prized catch for commercial fisheries due to their firm, flavorful meat, which is a favorite in many cuisines.

Key Differences Between Marlins and Swordfish

Although they look confusingly identical, there are tell-tale traits that easily distinguish marlins from swordfish. You just have to look at the right place to know which one is!


Marlins and swordfish have distinct classifications that set them apart. They fall under the same suborder, Xiphioidei, showing their close taxonomic relationship. However, their family classifications are different.

Marlins are categorized under the family Istiophoridae. This family includes various species of marlin. Meanwhile, the swordfish is the only species within the family Xiphiidae, classified scientifically as Xiphias gladius.

Physical Appearance

Marlin in deep blue waters

Marlins are known for their elongated, tubular bodies and a pronounced, spear-like bill, which is rounder and proportionately long compared to their body size.

They also have a sail-like dorsal fin that can be folded into a groove on their back for a more streamlined shape for swimming.

Swordfish up close

Meanwhile, swordfish have shorter, flatter bills relative to body size and a more robust and rounded body shape. Their shark-like dorsal fins cannot also retract and remain fixed, unlike marlins.

Adult swordfish also uniquely lose all scales and teeth as they mature, a feature not observed in marlins.

Also, marlins tend to be leaner and more elongated, while swordfish have sturdier, broader physiques.

These differences reflect adaptations to their lifestyles. Marlins’ retractable fins and longer bills are fit for quick bursts of speed to catch prey, while swordfish’s stout bills and scaleless bodies are designed for deep-water hunting.

Size and Weight

Marlin species have varying sizes, with the blue marlin being the largest, reaching lengths of up to 16 feet and weighing as much as 1,900 pounds. White marlins are generally smaller, maxing out around 180 pounds.

Swordfish also grow quite large, with an average adult reaching between 10 and 14 feet in length and weighing up to 1,400 pounds. They are robust, with a more solid body structure than the sleeker build of marlins.


Both marlins and swordfish demonstrate remarkable swimming capabilities, but the marlins, specifically the black marlin, stand out as the fastest species.

Marlins are among the ocean’s fastest fish, with the black marlin known for reaching up to 80 miles per hour. This rapid pace allows them to chase agile prey across vast ocean distances.

Meanwhile, swordfish are also incredibly fast and capable of impressive bursts of speed. They can reach speeds up to 60 miles per hour, which they use to overtake prey swiftly.

While swordfish are built for sudden, high-speed lunges, marlins are adapted for sustained high-speed pursuits.

Taste and Texture

Marlin, particularly the blue marlin, presents a distinct taste with a stronger, more pronounced flavor, similar to tuna but more intense.

Their white-to-pink flesh is firm and lean with a low-fat content. This makes marlins suitable choices for those who appreciate a heartier fish flavor. They are usually used in dishes like sushi and grilled steaks.

Meanwhile, swordfish offer a contrasting culinary experience. Their taste is milder and sweet, which appeals to those who prefer a less fishy flavor.

The texture of swordfish is dense and moist, thanks to its moderate oil content. Their raw flesh changes from a white or pinkish-orange to beige when cooked.

Swordfish steaks are often compared to beef steaks in terms of texture, making them an accessible option for those new to eating fish.

Habitat and Distribution

Marlins are mostly found in the warmer waters of the Atlantic, Pacific, and Indian Oceans, and they usually stay near the surface.

They inhabit areas where the sea temperature is balmy, preferring the sunlit zones. They frequently move between the surface and depths of 100 meters, although they can go as deep as 600 meters.

Meanwhile, swordfish have a wider habitat range, including warm and cool waters of the Atlantic, Indian, and Pacific Oceans.

They can dive into deeper ocean layers, reaching over 600 meters to find food. Interestingly, swordfish are less frequently observed at the surface and are more solitary than marlins.


Marlins primarily consume small fish, mackerels, and tunas. They are powerful predators, hunting solo in the vast open ocean. Their diet is varied but focuses on these agile and often fast-moving fish.

Meanwhile, swordfish feed on smaller fish and cephalopods like squid and octopus, hunting throughout the water column, from surface to seabed. They use their sharp bills to injure larger prey.

While both are adept hunters with a capacity for deep dives, their diets reflect their different hunting techniques and prey preferences.

Marlins typically target high-speed fish in the open waters, while swordfish are generalists, taking advantage of a wider range of prey throughout the water column.

Behavior and Lifestyle

Marlins are typically solitary creatures, predominantly leading a non-migratory lifestyle. They maintain a consistent territory throughout their lives, except when spawning.

Nonetheless, migratory behaviors may vary for marlin species. Blue marlin are known for their impressive migrations, while others, like black marlin, are less migratory.

On the other hand, swordfish are known for their solitary and group behaviors beyond the spawning season. Notably, they undertake extensive migrations driven by changes in water temperature and breeding cycles.

Both species spawn similarly; neither marlins nor swordfish nurture their offspring after release.

Swordfish tend to spawn in warmer waters year-round but switch to summer breeding in cooler regions.

Marlins, on the other hand, follow a more predictable spawning pattern, with seasonal egg-laying events that result in a quick hatching period of about a week.

The behavior of marlins and swordfish also varies when hooked. Marlins usually leap and bolt out of the water when caught, unlike swordfish, which swim deeper. This is very important to note if you plan to go fishing.

On one of my troll fishing trips in Florida, I experienced first-hand the challenge of fishing for marlins. It took me 50 minutes just to tire out and reel in the blue marlin that I caught.

If you want to try marlin or swordfish fishing, you should be ready for long waiting hours of trolling, besides the exhausting fight once you’ve hooked one. It is a lot harder than fly fishing for bass or other species!

Watch this video of a huge black marlin caught in Panama:

MONSTER Black Marlin Fishing in Panama


Marlins can live between 10 and 15 years. Swordfish, however, usually live shorter lives, with many reaching only about nine years. Factors like habitat, food availability, and human practices influence their longevity.

In the wild, marlins’ lifespan often depends on their ability to evade predators and fishermen. The lifespan of swordfish also faces similar pressures, but they generally have a faster growth rate, which may contribute to their shorter lifespan.

Frequently Asked Questions

Marlin swimming with a school of fish

Are Marlins and Swordfish the Same?

Marlins and swordfish are not the same. While they look almost identical, they belong to different families and species.

Furthermore, marlins have a more elongated body and a dorsal fin that runs along much of their back, while swordfish have a rounder body and a shorter dorsal fin.

Their behaviors and habitats also vary. Marlins are fast swimmers that can leap out of the water and tend to stay in warmer seas. Swordfish are known for their deep-sea diving and can inhabit both warm and cold waters.

How Fast Can Marlin and Swordfish Swim?

Marlins are among the ocean’s fastest fish, swimming up to 80 miles per hour. They are built for speed, with a sleek body that cuts through the water.

Swordfish are also swift, capable of swimming around 60 miles per hour. Their large, powerful tails propel them as they hunt for food.

Both marlins and swordfish use their speed to chase down prey, making them formidable predators in their marine environments.

Do People Eat Marlin and Swordfish?

Yes, people eat both marlin and swordfish, and they’re known for their firm, meaty texture. Swordfish is especially popular and widely available, often grilled or broiled.

Marlin is also consumed but is less common and can have a stronger taste. It’s often used in recipes like sushi and sashimi.

Next time you go fishing, you’ll definitely know what you are catching after understanding the differences between a marlin and a swordfish. What’s your take on these sea creatures? Let us know in the comments!

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