Ostracion cubicus

Common Names: Black-spotted boxfish, boxfish, cube trunkfish, cubical boxfish, polka-dot boxfish, spotted boxfish, yellow boxfish, Boston bean, etc.

Type Locality: India

Range: Extremely widespread, from the western coast of South Africa around to the Red Sea, then on across the Indo Pacific to Hawai`i and the Tuamoto Islands, north to Ryukyu Islands, south to Lord Howe Island; juveniles are also found in subtropical areas

Taxonomic Troubles: This is the original name, but the Red Sea population has been known as O. argus.

Size: 45 cm TL (18 inches).

Preferred Water Chemistry: Tropical marine.

Difficulty: Only for advanced aquarists with huge systems.

Tank Setup: The principal concern is size. This is a big fish.

Feeding: Will eagerly eat all types of foods but should have considerable vegetable matter.

Breeding: Not yet bred in captivity.

Fish Description

Bright yellow with black spots as juveniles. The fish darkens and loses the spots as it grows, with adults usually blue-grey with some yellow.


Like the related puffers and cowfish, boxfish are purchased by many people who should not acquire these animals. They are cute and colorful, and their engaging personalities, innate curiosity, and unusual locomotion seduce many hobbyists.

This group of fish, however, contains some real giants. Most of them grow too large for the typical home aquarium, and none are safe in a reef tank. Many are incurably nasty, and very few species can be kept with their own kind. In addition, they produce toxins that can wipe out an entire system. These toxins are released by stressed individuals and upon death. There are many cases reported in which every fish in the tank was killed by a toxic event.

This species is also a perfect example of a very appealing juvenile that grows into an 18-inch, drab adult that few people would select, even if they had a tank large enough. Aside from a puffer specialist with a suitably huge system, aquarists should leave this one in the sea.