Boxfish

Boxfish, from the family Ostraciidae, are some of the most structurally unique creatures in the ocean, characterized by a hard, triangular or box-like skeleton called a carapace. Because their bodies are encased in this bony “armor,” they cannot swim like traditional fish; instead, they use a method called ostraciiform locomotion. Boxfish oscillate their small fins to hover and pivot with surprising precision. Often referred to as “hovercrafts” of the reef, they have puckered, expressive mouths and large eyes that give them an almost puppy-like appearance. Many juvenile individuals begin their lives incredibly vibrant and colorful, but will lose their colorations as they mature.

Caring for boxfish is considered a high-level challenge due to their specialized needs and a unique defense mechanism known as ostracitoxin. When severely stressed or dying, some boxfish can release this potent toxin into the water, which can unfortunately be fatal to every inhabitant in the aquarium, including themselves. They are slow eaters and can easily be outcompeted for food by faster fish. They also require a diet of varied meaty foods and algae. While they are generally peaceful, they are not considered reef-safe as they may nip at tubeworms, mollusks, and some corals. Given their potential size and the risk of toxin release, they require large, stable environments and very careful selection of tank mates.