Marlin vs. Swordfish: Understanding the Differences

At a glance, marlins and swordfish could be mistaken for one another due to their impressive size and iconic, sword-like bills. However, despite these superficial similarities, each fish boasts unique characteristics that set them apart. Beyond family ties, their physical attributes tell a story of two different evolutionary paths tuned to their respective lifestyles in the ocean’s vast playground.

The Main Difference between Marlin and Swordfish

Marlin vs. Swordfish: Key Differences Between These Sea Creatures

Marlin vs. Swordfish: Key Takeaways

  • Marlins and swordfish are similar in appearance but hail from different families.
  • Physical distinctions include marlins’ sail-like dorsal fins and the scaleless bodies of adult swordfish.
  • Marlins and swordfish share oceanic habitats but exhibit unique behaviors and preferences.

Marlin vs. Swordfish: Overview

Understanding Marlin

Marlins are distinct fish characterized by their spear-like snout or bill and a pronounced dorsal fin that can resemble a crest. Our fellow marlins are equipped with a long upper jaw, used effectively to catch their prey, primarily consisting of squid and smaller fish. With bodies built for speed, marlins are some of the ocean’s most impressive predators.

Understanding Swordfish

When we look at swordfish, we’re examining a different class of ocean wanderers. These fish are known for their migratory patterns, traversing vast oceans and diving to significant depths as the seasons shift. Adult swordfish are identifiable by their round bodies and the loss of scales as they mature, differentiating them from the marlin with a dorsal fin shape that is more akin to a shark‘s.

Marlin vs. Swordfish: Physical Differences

To better understand the physical characteristics that set marlins and swordfish apart, we’ve compiled a table detailing their distinctive features. Let’s dive into those differences:

Feature Marlin Swordfish
Bill Sharply pointed, spear-like Broad, flat, and shorter
Dorsal Fin Prominent crest-like, elongated fin Tall, sickle-shaped fin
Body Shape More elongated More round and robust
Scale Type Dense, bony scales Lose all scales as adults
Size Large; can grow very big Typically smaller than marlin

Marlin vs. Swordfish: Habitat and Behavioral Differences


  • Marlins:
    • We commonly find marlins in tropical and subtropical waters around the globe.
    • These fish prefer the surface layer of the ocean, usually above the thermocline, where the water is warmer.
  • Swordfish:
    • Swordfish are quite the travelers and exhibit a broader habitat range, including temperate, tropical, and even colder waters.
    • They are known for their capability to dive deep into the ocean, often reaching depths where sunlight barely penetrates.

Behavioral Traits

  • Marlins:
    • We’ve observed that marlins are often seen near the surface, likely due to their diet which consists of smaller fish and cephalopods that inhabit the upper layers of the ocean.
    • Marlins are also known for their speed and agility, making them a favorite among sports fishermen.
  • Swordfish:
    • On the other hand, swordfish have migratory patterns linked to the seasons and can travel vast distances across the seas.
    • They are powerful swimmers as well, capable of handling the pressures of the deep sea during their food search, which includes a variety of fish and invertebrates.


  • Marlins: Small fish, squid, and sometimes crustaceans.
  • Swordfish: Widely varied; including fish, squid, and crustaceans found in deeper waters.

Marlin vs. Swordfish Examples in Sentences

Example Sentences of Marlin

  1. We caught a blue marlin off the coast last summer; its powerful leap was a sight to behold.
  2. Our fishing trip was remarkable; we hooked a striped marlin that weighed over 300 pounds.
  3. I read that marlins use their spear-like bills to stun prey, which is a key difference from swordfish.
  4. The marlin we saw had a distinctive dorsal fin; it was tall and formed almost a crescent, unlike swordfish which have a different fin structure.
  5. Marlins are among the most sought-after trophies for sport fishermen due to their size and agility in the water.

Example Sentences of Swordfish

  1. At the seafood market, we noticed the swordfish steaks were thicker compared to other fish, and they’re said to be quite flavorful.
  2. Swordfish are recognizable by their flat bills; they look quite different from the pointed bill of a marlin.
  3. We learned that swordfish can dive to great depths, much deeper than marlins, during their migratory journeys.
  4. Swordfish prefer warmer waters, which is why we observe them during our dives in the tropics.
  5. Despite their size, swordfish are capable of reaching speeds that rival those of the fastest marine creatures, similar to marlins.

Related Confused Words

Marlin vs. Sailfish

Marlins and sailfish share the family Istiophoridae, which can lead to confusion. We distinguish them by the sailfish’s smaller size and its characteristic dorsal fin, which is much larger and stretches down the length of the back, resembling a sail more than that of a marlin.

Swordfish vs. Sailfish

Although swordfish and sailfish have elongated bodies and long bills, they belong to different families—Xiphiidae and Istiophoridae, respectively. Swordfish are solitary with a rounder body, whereas sailfish prefer schools and showcase their sail-like dorsal fin.

Swordfish vs. Narwhal

Despite both possessing long, protruding features, swordfish and narwhals are distinct; a swordfish has a flat, sword-like bill, while a narwhal’s “horn” is actually a spiral tusk. Narwhals are Arctic cetaceans from the Monodontidae family, unrelated to swordfish.

Swordfish vs. Sawfish

Confusion arises here due to their similar names and long snouts, but a sawfish’s snout has teeth protruding from the sides, looking like a saw blade. Swordfish, on the other hand, have a smooth, pointed bill. Sawfish are rays from the Pristidae family, not fish closely related to swordfish.