Yellow Boxfish

The yellow boxfish is a small, cube-shaped reef fish easily recognised by its bright yellow body covered with black spots. Juveniles are especially vivid, often resembling tiny swimming dice. As they mature, their colour fades to a duller yellow or brown, but they keep their unmistakable boxy shape.

These quirky fish are found throughout the Indo-Pacific region, including on the northern coasts of Australia. They prefer shallow coral and rocky reefs, where they cruise around in search of small invertebrates, algae, and sponges to nibble on.

Despite their awkward shape, yellow boxfish are surprisingly agile swimmers. They use all their fins simultaneously to hover, pivot, and even reverse with precision. However, their rigid, bony carapace makes them slow movers compared to other reef fish.

One of their most unique features is their defence mechanism. When stressed or threatened, yellow boxfish can release a toxic substance called ostracitoxin from their skin into the water. This toxin can be harmful, even lethal, to nearby fish, which makes predators think twice before going in for a bite.

While small and shy in the wild, yellow boxfish are sometimes kept in aquariums. However, their delicate nature and toxic defence system mean they require very specific care.