Arabian Boxfish [Ostracion cyanurus]

Arabian Boxfish (Ostracion cyanurus)

The Arabian Boxfish is a highly distinctive marine boxfish from the western Indian Ocean, also commonly referred to in the trade as the Bluetail Trunkfish or Red Sea Boxfish. Adults show strong sexual dimorphism, with males developing vivid blue and green tones, while females are more yellow with blue spotting and reddish facial markings. In the wild, this species is found in the Red Sea through to the Persian Gulf, where it inhabits reef-associated areas with moderate coral growth and tends to stay close to shelter. Although striking and full of character, it is a more specialised species that is best suited to established marine systems and experienced aquarists.

Common Name:
Arabian Boxfish. Also traded as Bluetail Trunkfish and Red Sea Boxfish.

Scientific Name (Latin):
Ostracion cyanurus

Maximum Size:
Up to 15 cm.

Water Type:
Marine.

Origin / Natural Habitat:
Western Indian Ocean, from the Red Sea to the Persian Gulf. It is a reef-associated tropical species, typically found in areas of moderate coral growth, usually living solitarily and staying close to shelter.

Water Parameters:
Temperature: 22–28°C
pH Range: 8.1–8.4
Salinity: 1.020–1.025 SG

Temperament:
Generally peaceful, but shy and easily stressed. It is best housed with calm, non-aggressive tankmates rather than boisterous or territorial species.

Diet:
Omnivorous, with a herbivorous lean. Offer a varied diet including quality frozen foods, small meaty items and marine-based prepared foods. Newly imported specimens may respond best to more tempting foods at first before being transitioned onto a broader diet.

Minimum Tank Size:
500 litres minimum is advisable for long-term care.

Behaviour & Activity:
A slow, deliberate swimmer that spends much of its time investigating rockwork and hovering close to cover. This species is usually solitary and benefits from a calm aquarium with plenty of structure and refuge.

Reef Safe:
Reef Safe with Caution
There is mixed trade guidance on this species. Some suppliers list it as reef safe, while others advise caution or classify it as not reef safe because it may nibble tube worms and can be incompatible with some molluscs and crustaceans. In a reef system, monitor carefully around feather dusters, ornamental crustaceans and other delicate invertebrates.

Special Requirements or Care Notes:
This is a more specialist species that does best in a mature, stable marine aquarium. It is widely regarded as an expert-care fish, and one of the most important cautions is that boxfish can release a toxic substance when severely stressed or upon death, which can endanger other aquarium inhabitants. Careful acclimation, calm tankmates and excellent water quality are especially important.

Suitable for:
Experienced fishkeepers.

Availability:
Occasional in trade. This is an inference based on current specialist supplier listings rather than a formal trade-wide classification.