Swordfish vs. Marlin (Yes, They're Different Fish)

First things first: Swordfish and marlin are entirely different fish.

Swordfish belong to the Xiphiidae family, while both marlin and sailfish are part of the Istiophoridae family. That taxonomic split explains their major physical and behavioral differences.

The swordfish has a long, flat bill and a rounded body built for endurance in the deep water. It also sports a tall, crescent-shaped dorsal fin.

In contrast, marlins — including blue marlin, black marlin and striped marlin — tend to have more elongated bodies and a pointier, spear-like bill. Their dorsal fins are lower but extend further back.

In the open ocean, swordfish hunt in deeper waters, often going hundreds of meters down. They use their bills to slash at schooling baitfish, stunning their prey before gobbling them up.

Their ability to dive is aided by physiological adaptations, as swordfish lack swim bladders and rely on other mechanisms to control buoyancy at extreme depths.

Marlins, on the other hand, prefer relatively shallow water near underwater seamounts, the continental shelf drop off and other seafloor features where ocean currents attract bait.

Marlin fishing often involves trolling near the surface to attract schooling baitfish like flying fish or tuna, which are marlin favorites.

Both species are highly migratory, found across the Atlantic, Pacific and Indian Oceans. Anglers might catch swordfish off the Gulf, near land drops or in areas with high concentrations of bait. Catching billfish like marlin requires a keen understanding of seafloor features and a lot of patience.

Anglers looking to target swordfish often turn to deep dropping: using baited hooks lowered hundreds of feet. Marlins are more commonly caught with surface bait, sometimes even during daylight near the continental shelf.

Thinking of grilling some seafood? Swordfish steaks are popular for their firm, meaty texture and strong flavor. Their flesh is typically white with a hint of pink and holds up well to grilling.

Marlin flesh, in contrast, varies by species. Blue marlin has a rich, full flavor with a similarly firm texture. Some compare its taste to tuna, while others say it has a similar taste to swordfish, just less intense.

Whether you're aiming to catch, cook or just identify one of these oceanic heavyweights, understanding the subtle and not-so-subtle differences between them helps.

From their preferred depth in the water column to the shape of their bodies and fins, marlins and swordfish represent the diverse adaptations of fish species in the open sea.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.