Boxfish are a type of fish belonging to the Ostraciidae family of fishes. They are box-shaped and usually on the small side, not often exceeding five inches (12 cm) in length. A layer of bony plates on the scales helps to protect them against attacks by larger predators. Females are typically brown with white spots, and males are brown with blue, gold, and white spots. This type of fish is native to the Indo-Pacific ocean and can often be found near coral reefs, sand beds, and grass beds.
The average boxfish is non-aggressive by nature but may release a highly toxic poison when attacked or threatened. Sometimes it will also release it just after dying. This poison is capable of killing other aquatic life, including the fish that emits it. When the poison is released in nature, the boxfish normally swims away afterward to protect itself. Aquarium dwellers do not have this choice and often die as a result of spraying their own toxin.
Many people like to keep these fish in aquariums because of their bright colors and unique overall appearance. Other non-aggressive fish are generally the best options for aquarium mates. Putting them together with fish prone to fighting will likely result in the poison being sprayed. It is also not normally a good idea to place two male or two female boxfish together in the same aquarium because they may try to attack each other. If this occurs, and neither fish dies, chances are good that they will coexist peacefully afterward.
Boxfish are omnivorous, meaning they will eat both plants and meat. Some of the more common items they eat include crabs, shrimp, clams, seaweed, and coral. Boxfish are often slow eaters and may seem like they never have much of an appetite. It is usually not a good idea to feed them anything that floats on the surface of the water because they tend to become very disoriented after accidentally gulping air.
Other closely related fish also in the family Ostraciidae are cowfish and trunkfish. The cowfish is yellow with blue spots and horns on its head and a lower fin for defense. Trunkfish are generally very similar to the boxfish in appearance, but they often become much larger. Some trunkfish grow to a length of 12 inches (30 cm). Most fish in this family are alike in regard to temperament, habitat, diet, and defense with some slight differences in appearance.