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What is a Billfish?

A billfish is a term for predatory fish known for their elongated bills, resembling a spear, used to slash through schools of prey. Species like marlins, sailfish, and swordfish fall under this category, each boasting impressive speed and size. Intrigued by these oceanic athletes? Dive deeper to uncover the secrets of their underwater ballet and their role in marine ecosystems.
Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

A billfish is a fish with an elongated upper jaw and snout. The most well known example of a billfish for some people is probably the swordfish, which sports an impressive jaw which looks like a heavy sword or spear. Billfish species can be found all over the world, and unfortunately their populations are under threat in some regions due to heavy fishing for these popular food and game fishes.

The term “billfish” is used to describe fish in two families: Istiophoridae and Xiphiidae. Istiophoridae includes both sailfish and marlins, two popular game fish which can be found in regions ranging from the tropics to the temperate zones further north. The family Xiphiidae has only a single species, Xiphias gladius, otherwise known as the swordfish.


In addition to sharing a distinctive bill, billfish are also generally extremely strong, intelligent fish. This makes them a popular choice as a game fish, since they generally put up a fight which can challenge even a skilled fisherman. The muscular, dense flesh of some species is also enjoyed as a source of food; swordfish is probably the most popular food fish in the billfish grouping. Some billfish are capable of launching themselves out of the water with their powerful fins and muscular bodies, which can be quite a sight.

Billfish are also predatory, and they are among the top tier of predators in the ocean. They can grow to be quite large, feeding on an assortment of smaller fishes. Some individuals have also been known to attack larger fish and even humans; scientists have reported attacks on research submersibles in which billfish have actually buried their jaws in window portals.

Concerns about overfishing of billfish have led to some measures around the world to preserve these unique fish. Many sport fishermen voluntarily participate in catch and release programs, for example, and several organizations track catch and release data sent in by fishermen. These groups hope to restore billfish stocks by restricting the annual harvest, in the hopes that populations will remain diverse and strong.

Consumers who are concerned about sustainable fishing may want to seek alternatives to billfish. Halibut and mahi mahi are both good alternatives with firm, white flesh which can behave a great like like billfish when cooked. If sustainable fishing is not a major concern for you, you may want to limit your intake of billfish such as swordfish anyway, since these fish species bioaccumulate mercury and other environmental toxins.

Mary McMahon
Mary McMahon

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

Learn more...
Mary McMahon
Mary McMahon

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

Learn more...

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Discussion Comments


I am part of an organization based out of Florida called the Billfish Foundation. We aim to protect the populations of these incredible fish and to see that they are fished in sustainable ways. Our organization is really not significantly different from many other organizations which advocate on behalf of a species of geography.

We have had some success but there is still a long way to go. Billfish populations around the world are threatened by a whole host of factors and it is only with careful vigilance and dedicated action that we can ensure these beautiful fish thrive into the future.


My dad used to have a giant stuffed Marlin that he kept on the wall in his den. I think this qualifies as a billfish. It certainly has the jaw for it.

As a kid my brother and I were fascinated by it. My dad forbid us to touch it but we could sit and stare and that we did. My dad had caught it on a fishing trip when he was about 30 and it was the prized piece in a collection of hunting and fishing trophies that he amassed over the years. When he passed on, the Marlin went in the trash, but in hindsight I wish that someone would have kept it.


To me, swordfish is a delicacy. I absolutely love its texture, and you can always taste its signature flavor through whatever seasonings have been applied to it.

I only get to eat it about twice a year, when I go to the Gulf coast on vacation. I always dine at nice seafood restaurants while I'm down there, and if swordfish is on the menu, I'm positively going to order it.

It's a good thing that I don't live down there, because I might singlehandedly contribute to the decline of the billfish population. I also might suffer from mercury poisoning!


@shell4life – The men in my family have been avid billfish hunters for years, so they know how sad it can be to no longer be able to keep their catch. They still enjoy the sport, though.

My brother loves to go fishing in a couple of bays in Alabama. He finds a lot of longnose gar here, and they resemble swordfish so much that I can't tell the difference.

I have seen alligator gar, the cousin to the longnose gar, in freshwater lakes. They look just like the billfish, with their long snouts filled with scary little teeth. Their snouts look like they could be snapped off the dead fish and used as saws!


My uncle loves fishing for billfish. He used to try to outdo his own record. He had the largest swordfish he had ever caught mounted on his wall, and he constantly tried to catch a bigger one to replace it with.

Now, he merely catches and releases them. He doesn't want to harm the population, so he simply takes photos of the big ones he catches, rather than using them as trophies.

He is extremely proud of the one he does have on his wall, though. I hope nothing ever happens to it, for his sake.


Though I used to consume swordfish often, I am now scared to eat fish that contain lots of mercury, so I avoid tuna and billfish. I do like halibut, and since its level is relatively low, I eat it once every week.

I like to cook it in melted butter. I sprinkle dill, cajun seasoning, and lemon juice on the fish and in the pan, and I cook it on top of the stove.

After one side is done, I flip it over and cook it some more. I know that the halibut is ready to be eaten when pieces of it can easily be flaked off with a fork.

The texture is so much like that of swordfish that I don't miss it at all. Also, the seasonings manipulate the flavor to remind me of the way I used to cook swordfish.

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