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Boxfish Facts

Size 8-10 inches (20-25 cm)
Speed Unknown
Weight Unknown
Lifespan 4 years
Food Crustaceans, sea urchins, mollusks
Predators Large fish, sharks
Distribution Atlantic, Pacific, Indian Ocean
Habitat Tropical seas, coral reefs, seegrass meadows
Order Cottidae
Family Tetraodontiformes
Scientific name Ostraciidae
Characteristics Tropical fish with a square body, related to pufferfish

Main Characteristics

Boxfish have a square or rectangular, angular body. Some have long horns on their heads – like cows. Their funny appearance is matched by their funny swimming style, as they often appear to "sway" while swimming. They're closely related to pufferfish.

Longhorn Cowfish Longhorn Cowfish - Photo: Khoroshunova Olga/Shutterstock


There are over 20 species of boxfish. The most famous are the spotted and smooth trunkfish, honeycomb, longhorn, thornback and camel cowfish.


Distribution and Habitat

Boxfish live in the Atlantic, Pacific and Indian Oceans. They prefer shallow, tropical seas and tend to live near the coast, inhabiting coral reefs and seagrass meadows. They are often seen a few meters below the surface, but can dive up to 160 feet (50 meters) deep.

Life Style

Boxfish are active during the day. Depending on the species, they live in pairs or as solitary creatures. They spend their time searching for food in the sand or for a mate to reproduce.


Boxfish are omnivores. They feed on worms, tunicates, sponges, algae, sea grass, small fish and crustaceans.

Boxfish Characteristics Boxfish Characteristics - Photo: Michael Apel [CC BY-SA 3.0], via Wikimedia Commons

Anatomy and Appearance

Size and Weight

Boxfish can grow to 17-20 inches (45-50 cm) long. However, usually their length is only 8-10 inches (20-25 cm).


Body Shape

Boxfish have an angular body that is square to rectangular. Under their scales they have a solid carapace made of bony plates.


Many boxfish have horns on their heads. In longhorn cowfish they are particularly long.


Boxfish are colorful fish. The spotted and smooth trunkfish have lots of black or white spots. The honeycomb cowfish has a pattern that resembles the honeycombs in a beehive.

Boxfish or Puffer Fish – What’s the Difference?

The main difference between the two families of fish is: Pufferfish can inflate themselves. Boxfish don't. Their carapaces are too rigid and inflexible for that. Both are poisonous, but only the pufferfish is poisonous enough to kill a person.

Boxfish or Pufferfish - Differences Boxfish or Pufferfish - Differences - Photo: ickard Zerpe (boxfish) [CC BY-SA 2.0], via Wikimedia Commons, Aries Sutanto (pufferfish)/Shutterstock



Boxfish have a diverse diet that includes not only algae and seaweed, but also small worms and crustaceans that hide in the sand. To locate their prey, they have a trick: blowing into the sand to create a powerful jet of water that uncovers their food.

Senses and Abilities

Color Change

Boxfish can change their color by contracting or expanding color cells – and do so extremely quickly. They change their color to communicate with others, to camouflage themselves or to scare off enemies.


Boxfish are slow swimmers. Their body is very stiff due to the bony plates under their scales, which is why their movements may give the impression of tumbling or stumbling. Actually they're adept at navigating and can effortlessly spin around at a remarkable speed.

Smooth Trunkfish Smooth Trunkfish - Photo: Kris Mikael Kriste [CC BY 3.0], via Wikimedia Commons



Boxfish can change color. When threatened, they quickly change to bright, vibrant colors to scare off potential attackers.


Boxfish can release a poison into the water through their skin. They do this when they feel cornered. No need to worry, the venom of these creatures is not as potent as that of pufferfish and poses no threat to a person in good health. Nevertheless, it can be fatal to other fish.


Their long horns make it difficult for predatory fish to swallow them.


Boxfish have a tough, sturdy carapace that is hard to break. Predatory fish usually can't eat them because they risk suffocation if they attempt to.

Yellow Trunkfish Yellow Trunkfish - Photo: iliuta goean/Shutterstock

Life Expectancy

In the wild, boxfish live for around four years.

Enemies and Threats

Natural Enemies

The boxfish's enemies are large fish and sharks.

Are Boxfish an Endangered Species?

No, boxfish aren't (yet) considered endangered.

Importance for the Ecosystem

Boxfish feed on algae and seaweed, thereby preventing the plants from taking over.

Young Boxfish Young Yellow Boxfish - Photo: Kolevski.V/


The knowledge about the mating and reproductive behavior of boxfish is limited. We do know that male boxfish establish and protect their own territories. Females lay eggs that are fertilized by the males. The eggs hatch into larvae after one or two days, and these young fish initially have a rounder shape and more vibrant colors compared to the adults. It is said that a female is capable of laying eggs every day for a month.

Boxfish as Pets

Box fish are incredibly adorable. Who wouldn't love to have them as pets? However, it's important to be aware that boxfish come with a few drawbacks. Firstly, all species of boxfish grow 8-10 inches (20-25 cm) long. You will need a sufficiently large aquarium. Male boxfish typically have a territory of 5,400 square feet (500 m²) - the size of a huge house with six bedrooms and four bathrooms. If they feel threatened for any reason, they release a poison that can kill all aquarium inhabitants (including the boxfish itself).

Honeycomb Cowfish Honeycomb Cowfish - Photo: LASZLO ILYES from Cleveland, Ohio, USA [CC BY 2.0], via Wikimedia Commons


What Do Boxfish Have to Do With Cars?

Boxfish, despite their unique body shape, exhibit minimal resistance to water flow, which is why they require little energy to move around. Inspired by this, the car manufacturer Mercedes-Benz produced a car called the “bionic car” in 2005. Its shape resembled the shape of the yellow boxfish. Tests shows, that the car had minimal air resistance compared to other vehicles. However, in 2015 a study found that the flow resistance of boxfish is significantly higher than previously thought. How could the car have such impressive drag-reduction capabilities? Well, it wasn't exactly shaped like a boxfish, it just looked similar. The car manufacturer did a great job.

Boxfish Help Improving Protective Vests and Robots

The boxfish's carapace consists of small hexagonal shaped, bony plates that look like honeycombs. Scientists find the carapace's ability to provide rigidity and resistance fascinating. They are currently exploring its potential to enhance protective vests, such as those used by the police, as well as the armor of robots.

Fun Facts

In German, boxfish are called Kofferfisch, which means „suitcase fish“.

The Boxfish Is Related To:

  • Porcupinefish
  • Pufferfish
  • Sunfish

Animals in the Same Biome:

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