Are boxfish poisonous? You may have heard that boxfish are the most dangerous fish in the world. And indeed, there are several species of boxfish that are quite venomous and even potentially deadly. But in truth, these shy and reclusive fish (also known as cowfish or sea coffer) aren’t really dangerous at all. Most species are completely harmless to humans. If you’re thinking about getting an aquarium, rest assured that even the most dangerous boxfish are not a threat to you or your home. Here’s what you need to know about these unique marine animals—and why you should never keep them in a home aquarium if you ever meet one in the wild!
What is a boxfish?
A boxfish is any member of the family Ostraciidae. There are around 200 species of boxfish, most of which are marine fish but a few species inhabit freshwater. They are found throughout the world in tropical and subtropical waters.
The bodies of boxfish are covered with large, rectangular plates that give the fish their name. The plates are made of keratin, the same material that forms human hair and nails. The plates are not connected, but they do overlap slightly. T
hat allows the fish to change the shape of its body for swimming, moving the plates to create fins, or even climbing out of the water to escape predators. Boxfish are largely solitary and reclusive, living in crevices in the reef, on sandy or muddy bottoms, or in caves, often at great depths.
They are not very active and usually extend their swimming only within a very small territory around their retreat and bottom.
The most dangerous boxfish
The most dangerous boxfish is the blue-spotted boxfish (or cobalt stinger, variously). It lives in warm oceans, especially the Indian Ocean and the Pacific Ocean. The blue-spotted boxfish is a small fish that can grow up to only about 4 inches long.
It has large, bright blue spots on its body and a very long, thin, curved spine that can inject a very painful venom. This species of boxfish is very poisonous to humans, and the sting is usually very painful but not usually fatal.
Likely, other species of boxfish may also be poisonous, but the blue-spotted boxfish is the only one for which there is medical confirmation.
Why are Boxfish Dangerous?
The blue-spotted boxfish can expand its body and change shape using a large number of scaly plates and spines that cover its body. Each of these scales has a small venom gland connected to it. If a predator attacks the boxfish, the boxfish can voluntarily open the venom gland and the scale will release its venom into the water.
The venom acts as a highly potent neurotoxin that paralyzes or even kills the attacker. The blue-spotted boxfish is the only species of boxfish that has been confirmed as being dangerous to humans. In general, all other boxfish species have very small amounts of non-dangerous venom that are used for self-defense only.
The blue-spotted boxfish is an exception to this as it has a very potent venom that can even kill people who are allergic to it!
Which species of Boxfish are the most dangerous?
The blue-spotted boxfish is the most dangerous fish in the world. There are many other species of boxfish that are also venomous. So which other species of boxfish are the most dangerous? There are around 200 species of boxfish, and the vast majority of them are not dangerous to humans at all.
However, some species of boxfish may be dangerous. The following boxfish are described as “dangerous” or “poisonous”:
- The Blue-spotted boxfish, or cobalt stinger is the most dangerous boxfish. It is found in warm oceans, especially the Indian Ocean and the Pacific Ocean.
- The Blunt-nosed or blue-spotted boxfish is found in the Atlantic Ocean in the Caribbean and Gulf of Mexico.
- The Blue-eared or yellow boxfish is found in the Indian Ocean, the western Pacific Ocean, and the western coast of Australia.
- The Blunt-nosed or blue-spotted boxfish is found in the Atlantic Ocean in the Caribbean and Gulf of Mexico.
- The Humpback or white boxfish is found in the western Pacific Ocean.
- The Triangle-tailed or black boxfish is found in the western Pacific Ocean.
- The Northern or white boxfish is found in the Indian Ocean, the western Pacific Ocean, and the western coast of Australia.
- The Ornate or white boxfish is found in the western Pacific Ocean.
How to know if a Boxfish is “Dangerous” or Not?
The only way to know if a boxfish is dangerous or not is to get bitten by it. If you are bitten by a boxfish, you may experience a burning sensation or pain at the site of the sting followed by swelling, numbness, and muscle spasms.
If the boxfish is poisonous to humans, you may experience difficulty breathing, dizziness, nausea, and vomiting. Seek medical attention immediately if you have any of these symptoms after being bitten or stung by a boxfish.
Unfortunately, there is no easy way to tell whether or not a boxfish is poisonous, and it is impossible to predict which species of boxfish may be dangerous.
Conclusion
Boxfish are not a danger to swimmers as they are too slow to catch prey. They are reclusive and slow-moving fish that spend much of their lives hiding in crevices in the reef or on the ocean floor. They usually extend their swimming only within a very small territory around their retreat and bottom.
Boxfish are not dangerous to you unless you provoke them or try to touch them and get bitten. If you’re in the water and see a boxfish, just leave it be. And if you’re on the shore, you might even get lucky and get to see one swim right up to you.
This shy and curious fish may swim up to you and even let you touch it. So if you ever meet a boxfish, remember that it is shy and reclusive and won’t hurt you.
