Hawaii Reef Fish Guide
Boxfishes
Boxfishes look like little armored reef fish, with hard shell-like bodies and small fins that move them carefully through the water. In Hawaii, they are called pahu, meaning “box,” a name that fits their unusual shape.
Boxfishes in Hawaii
Boxfishes are some of the easiest reef fish to recognize in Hawaii because their bodies look stiff, hard and almost box-shaped. In Hawaiian, they are called pahu, meaning “box.” Five species of boxfish can be seen in Hawaiian waters.
Their bodies are covered by a hard shell made of fused bony plates. Because this outer covering is so rigid, boxfishes do not bend their bodies the way many fish do. Instead, their eyes, fins and mouth move freely while the rest of the body stays firm.
How Boxfishes Move and Feed
Boxfishes often swim slowly and carefully over reefs, coral rubble and rocky areas. Their small fins help them steer with precise movements, giving them a gentle, floating look compared with faster reef fish.
They feed on algae, worms, small crustaceans, sponges and other reef foods. Their small mouths help them pick food from reef surfaces and tight spaces. Many boxfishes are seen alone, though they may come together during mating behavior.
Defense and Safe Viewing
Some boxfishes can release toxic mucus when stressed. This helps protect them from predators, but it is another good reason not to chase, touch or corner them. In the open ocean, the fish has room to move away, but in small aquariums this toxin can harm other fish.
For snorkelers and divers, the best approach is simple: watch calmly and give boxfishes space. Their shape, slow swimming and Hawaiian name make them a memorable part of Hawaii's reef life. Related pages include the Hawaii fish guide, pufferfishes, filefishes, triggerfishes and Hawaii snorkeling.
