What is a Swordfish?

Mary McMahon
Mary McMahon

The swordfish is a perciform fish found throughout the world, and instantly recognizable by its sizable upper jaw, which resembles a sword protruding from the front of the fish. It is popular for eating and sport, and the fish is caught all over the world along long migrations in search of prey. The conservation status of this fish is unclear, although several nations have noticed a decline in stocks and have closed swordfish nurseries to fishing as well as monitoring catches more closely.


In addition to the distinct upper jaw, swordfish also have crescent shaped rear fins and a tall front dorsal fin. The fish are generally gray blue to bronze on top, and pale cream on the bottom. They have streamlined bodies designed for rapid, efficient swimming, and are also extremely strong. They are voracious predators, eating a wide range of other fish species throughout the world's oceans. They have few predators as adults, other than humans, with the exception of some whale species.

Adult swordfish can reach lengths of 15 feet (5 meters) and weigh 1,400 pounds (650 kilograms) at maturity. Female swordfish tend to achieve larger sizes than males. In temperate areas, these fish spawn year round, temporarily pairing up with a partner to fertilize the eggs. In colder climates, spawning occurs in the spring and summer. The eggs float for several days before hatching into small larvae, which are often consumed by a number of larger fish. If allowed to grow, the fish will reach maturity in five to six years and can expect to live until approximately ten years of age.

The flesh of these fish is dense and white, well suited to grilling, baking, and saute. However, the flesh accumulates mercury at a high rate. As a result, consumers are not encouraged to eat swordfish and should limit their intake of the flesh to avoid bio-accumulation of mercury in their own tissues. Globally, sales and catches have declined since the 1970s, when the public was first alerted to the mercury risk.

Conservationists have raised concerns about these fish, as the majority of fish taken are young adults and juveniles. Because swordfish takes some time to mature, biologists suspected that excessive culling of juveniles might result in weaker stocks in years to come, and encouraged more controls on fisheries. In response, many nations enacted bans of fishing in known nursery areas, as well as size limits and more careful monitoring of on-board catches.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


The easiest way I have found to cook swordfish is on the grill. I cook it just like I would a steak and make sure that it doesn't get too dry.

It only takes a few minutes on each side and tastes wonderful. I always cook swordfish with the skin on because it helps keep the meat moist.

Once I am ready to serve it I just remove the skin. I also like to have lemon wedges cut up and drizzle some lemon over it before serving.

I have served this to people who really don't like the taste of fish and they will eat it with no problem.


I enjoy eating just about any kind of fish, but have a recipe for baked swordfish that is really good and very easy to make.

I marinate the fish in a mixture of lemon juice, soy sauce, garlic and ginger. I will also add some salt and pepper to taste. I put the fish and marinade in a bag and refrigerate for a few hours.

Once it is been marinated all I do is bake it in the oven for about 15 minutes. I will usually eat this with a salad and baked potato.

This meal if one of my favorites and is pretty easy to make. You can't really go wrong with the marinade sauce and can substitute things that you like and go well with fish.


@SailorJerry - I was just helping a student research this for a health class paper. Apparently, mercury gets into the water from water pollution, and fish then absorb it. It accumulates in their tissues and is not excreted.

So the longer a fish lives, the more mercury will be in its tissues. But also, if a fish eats algae or another fish, it winds up absorbing the mercury from its food as well. As you move up the food chain, the mercury levels gets higher and higher because the fish are getting all the mercury from the fish their prey ate, too.

So swordfish has really high levels because of being a predatory fish, higher up on the food chain.

If your wife plans to breastfeed, she should continue to lay off the swordfish until baby is weaned. But don't worry, you'll be back to your favorite swordfish recipes before you know it!


My wife was a big fan of swordfish, especially grilled, but now she's pregnant. We could eat it once in a while before, but now that she's expecting, it's on the absolutely not list. It is a no-no for pregnant women, as opposed to tuna, for instance, which they say pregnant women can have in moderation.

I also read recently, though, that canned tuna has surprisingly high levels of mercury. We've been eating a lot of salmon, as this comes in cans like tuna and has such nice good-for-you fat but not so much (or maybe not any?) mercury.

Does anyone know what makes some fish have a lot of mercury, while others don't? What's the difference?

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