The bluespotted boxfish is a beautiful fish that is not really suited for a marine aquarium unless you are willing to devote a tank to it. This fish is well known for releasing a poison, called ostracitoxin, if it is under any stress; this can quickly kill an entire tank of fish, including the boxfish itself. Its beauty merits a species tank, however. The male has the blue spots on its sides, while the female arise uniformly brown with white spots. You can keep a single male, single female or a pair -- just don’t try to keep two males together.
In addition to its nasty habit of occasionally poisoning its tank, bluespotted boxfish can be difficult to feed. Because it is usually not fed while in transit from the wild to the local fish store (which can take weeks), sometimes it just doesn’t start eating again. Before you purchase one make sure that you see it eating heartily. It may require live food to start with in the form of enriched live brine shrimp, guppies or mollies or other live fish. It also requires vegetable matter, and it will scrape at algae in a tank, but should also be offered any of the frozen foods made especially for herbivores. Needless to say, the bluespotted boxfish is not at all suitable for a reef tank, as it would consider everything in the tank in terms of corals, shrimps, crabs and algae as being part of its personal dining cart.