The Brackish Aquariumin General

Boxfish in the Aquarium

Boxfish, trunkfish, cowfish are all names for the same fish, which is part of the Ostraciidae family in the Tetraodontiforme order. Members of this order include many diverse species such as the puffer fishes, trigger fishes, and filefishes, each specializing in its own defense tactic. Puffer fish literally puff up to deter would be predators by appearing much bigger than they actually are. While trigger fish, along with filefish, have a “trigger” that is actually their first dorsal spine and when locked by their second dorsal spine, can lodge them selves into a crevice that can make it hard to nearly impossible for predators to dislodge them.

Boxfish are protected by a hard carapace made up of pentagonal shaped scales. This carapace has openings for the eyes, mouth, fins, and gill slits. The only unprotected part of the fish is the caudal peduncle. Some species incorporate sharp projections that resemble horns to their bodies, hence the name cowfish. All boxfish species have the ability to release a poison called ostracitoxin. This poison, when released in the aquarium, can cause a whole aquarium to be wiped out leaving the boxfish itself dead. Reasons for a boxfish to release this poisonous chemical can be things such as an aggressive tank mate harassing the boxfish or when it is stressed by something in the tank. Species that are best known for releasing their ostracitoxin are the blue boxfish while the humpback turretfish has no known history of releasing it in the home aquarium.

Tank Setup
Boxfish are marine fish and therefore need a saltwater aquarium. Depending on the size of the fish these aquariums can be anywhere from 55-100+ gallons. Some species of boxfish, such as those from Australian waters, require temperate (coldwater) marine aquariums which require chillers or other methods of cooling the water to a comfortable 60-69 degrees Fahrenheit. The majority of boxfish require a tropical marine aquarium. Since boxfish have a high waste output good filtration is essential. Incorporating a sump into the tank is a good idea whether it’s a tropical or temperate tank. Live rock also helps with biological filtration. However, keep in mind when setting up temperate biotopes that temperate reef rocks are denser than the average tropical reef rock so the tank does not benefit as much from biological filtration. Boxfish also require a tank that will stimulate them or they will get bored and swim along the sides of the glass. Interesting rock formations and designs that incorporate numerous hiding places are good stimuli.

A boxfish diet should include meaty foods such as shrimps, crabs, mussels, and crabs. Vegetarian foods are just as important in a boxfish’s diet as meaty foods. Frozen peas, boiled lettuce, or dried seaweed will suffice. Remember to keep the diet of the boxfish varied and alternate between frozen foods and live foods. A boxfish will enjoy hunting out its food. They may have a harder time getting to the food before other faster fish. Distribute the food over the tank, keep only boxfish in the tank, or put food directly in front of the boxfish.

Invertebrates form a natural part of the boxfish’s diet. It will most likely attempt to eat the invertebrate or coral. However, some boxfish will not eat invertebrates. A good way to test this is to place an inexpensive coral/invertebrate with the boxfish and see if it goes after it. Keep in mind that a boxfish may stray into a large anemone causing the fish to get severely injured, slightly wounded, or even resulting in its death. This also may cause the boxfish to release its ostracitoxin.

When acquiring new tank mates or putting a boxfish with existing ones, make sure that the tank mate is not an aggressive species that would bother the boxfish, won’t harm it or cause it release its ostracitoxin. Regarding seahorses, though boxfish and seahorses are both slow moving fish, when algae grows on a seahorse or it has algae looking body parts a boxfish may find it tempting to have a bite This could result in an injured seahorse. Therefore when picking out a seahorse make sure that it doesn’t have algae like body parts.

Overall, boxfish make great aquarium inhabitants. They are aesthetically appealing and are amusing in the aquarium, blowing jets of water into the sand or simply swimming around in their helicopter like fashion. A boxfish can be a great aquarium inhabitant as long as it is well cared for.