Species NameOstracion cubicus (for the Yellow Boxfish as an example)
Common NameBoxfish, Cube Boxfish, Yellow Boxfish
Care LevelModerate to High
LifespanUp to 10 years
Adult Size6 – 18 inches (varies by species)
Minimum Tank Size125 gallons
Temperature72°F – 78°F (22°C – 25.5°C)
Water ConditionspH 8.1-8.4, Salinity 1.020-1.025, dKH 8-12

About the Boxfish – Species Summary

Boxfish are captivating marine creatures, easily identified by their unique, cube-like shape and vibrant colors. Hailing primarily from the Pacific and Indian Oceans, they are most commonly found around coral reefs and rocky substrates. This distinctive fish has a hard, armor-like exterior made up of fused plates that shield them from many predators. While they bring a unique aesthetic to aquariums, they require specific care due to their sensitive nature and potential to release toxins when stressed.

Boxfish Lifespan

Boxfish can live up to 10 years in captivity when provided with optimal care. Their lifespan greatly depends on factors like diet, environmental conditions, and overall well-being. However, achieving such a lifespan requires dedication from aquarists, as they can be susceptible to various diseases and can be sensitive to sudden changes in their environment.


Their most defining feature is, of course, their boxy appearance. The body of a boxfish is encased in a rigid, bony, hexagonal plate structure. Depending on the species and age, they can exhibit colors ranging from bright yellow, blue, brown, to even green, often adorned with spots or patterns.

Average Size

While the size of a boxfish varies based on its specific species, most will grow between 6 to 18 inches in length. Some species remain small, making them suitable for home aquariums, while others might require larger, specialized setups.

Boxfish Care

Tank Size

A minimum of 125 gallons is typically recommended for boxfish, providing them enough space to swim, forage, and express natural behaviors. For larger species or if one plans to house multiple boxfish, an even more spacious tank is ideal.

How To Set Up Their Tank

Boxfish thrive in environments that resemble their natural habitats. Incorporate plenty of live rock, caves, and crevices to give them hiding spaces. A sandy substrate is preferable. Keep in mind their cube-shaped bodies; ensure there are no sharp edges or tight spots where they can get stuck.

Lighting Requirements

Moderate lighting is suitable for boxfish. However, if the tank contains live plants or corals, their lighting needs may need to be prioritized.


Maintain a stable pH level between 8.1 and 8.4 for the best health of boxfish.


An optimal temperature range for boxfish lies between 72°F and 78°F (22°C to 25.5°C). It’s crucial to have a good-quality aquarium heater and regularly monitor the temperature to ensure consistency.

Water Parameters

For boxfish, aim for a salinity between 1.020 and 1.025, and dKH levels between 8-12. Implementing regular water changes and using high-quality marine salt can help maintain these parameters.

Disease Potential

Boxfish can be prone to parasitic infections, bacterial diseases, and nutritional deficiencies. Employing a quarantine process for any new tank additions and regular health checks can help in early detection and treatment.

Food & Diet

Boxfish are omnivores. In the wild, their diet consists of algae, small crustaceans, and various marine worms. In captivity, they can be fed a mix of live and frozen foods like shrimp, squid, and marine algae. Providing a diverse diet is crucial to their well-being.

Behavior and Temperament

Boxfish are generally peaceful but can be territorial with their own kind or similar-looking fish. They’re often observed leisurely swimming and foraging throughout the day. When threatened, it’s essential to note that boxfish can release a toxin called ostracitoxin, which can be harmful to other fish in the tank.

Tank Mates

Boxfish coexist well with many non-aggressive marine species. However, given their potential to release toxins, it’s crucial to monitor them and avoid placing them with aggressive species that may harass or stress them.


Breeding boxfish in captivity is rare and challenging. Their unique body shape makes egg-laying and fertilization a meticulous process. If one wishes to attempt breeding, it’s essential to provide an environment mirroring their natural conditions, ensure a balanced diet, and maintain excellent water quality.

Boxfish FAQs (Frequently Asked Questions)