Easy Ways to Tell the Difference Between a Marlin and Swordfish


If you’re like most people new to sport fishing, you may consider swordfish and marlin to be the same type of fish. Even though these two large marine creatures have similarities, they’re different in several ways, such as their size, their fins and taste.  Here are three ways they differ, along with some suggestions on how to prepare marlin and swordfish dishes.  


If you’ve ever read Ernest Hemingway’s The Old Man and the Sea“, you may remember how an old fisherman struggled to catch a marlin.  Their most distinguishing features are their spear-like snout or bill and dorsal fin, which forms a crest, reaching forward. The upper jaw of a marlin is long. Furthermore, the spear can be deadly to prey, which is primarily squid and smaller fish. This makes marlins one of the top sea predators.

Marlins have a reputation for being exceptional swimmers as they can swim as fast as 50 mph. These popular, strong sporting fish can be found in the deep-sea tropical regions of the Pacific, Atlantic and Indian Oceans. They have a long lifespan with females living as long as 30 years and males reaching around 20 years.


Also known as broadbills, swordfish are salt-water, predatory and migratory fish characterized by their flat, long bill. Their bodies are round and elongated. They get their name from their bill, which resembles a sword. Interestingly, you can determine their age by looking at their annual growth rings that can be found on the fin rays.  

These fish have a heating mechanism, found next to their eyes, that helps in conserving heat. Besides conserving heat, this heating mechanism also helps with their vision, and makes them better hunters. Used much like a spear, their swordlike organ is designed for slashing prey.



Although marlin and swordfish are both large fish, there are several differences, such as:

  1. Differences in size

One way to tell the difference between a marlin and a swordfish is size. In fact, the largest marlin species is longer than 16.4 feet, weighing up to 1,400 pounds. Yet, swordfish are smaller, reaching 9.8 feet and weighing 1,430 pounds.  

  1. Differences in fins and bodies

 Another difference is their dorsal fins, which are the fins on their back. While a marlin’s dorsal fin resembles a sail, the fins on the back of a swordfish look much like those of a shark’s fins. What’s more, marlins have tubular, smooth bodies, which is unlike the elongated, round bodies of swordfish.

  1. Differences in taste

The pink flesh of marlin tastes much like swordfish, but swordfish is considerably lighter. Marlin is a fatty fish, consisting of a high-fat content. Thus, marlin flesh is very dense, similar to tuna, having a strong flavor. On the other hand, marlin has a milder flavor than that of swordfish.