
Source: Wikimedia Commons
Ostracion cubicum
The boxfish famous for its yellow dice-like juveniles with black spots. It turns brown with age and reaches 45cm. It releases toxin when stressed, so it is an advanced species kept alone.
The Yellow Boxfish (Ostracion cubicus, valid name Ostracion cubicum) is an ostraciid ranging from the Red Sea and East Africa to Hawaii and north to the Ryukyu Islands. It inhabits lagoons and semi-sheltered seaward reefs at 1-280m, usually shallower than 50m. Juveniles shelter among Acropora branches and their bright yellow cube-shaped bodies with black spots make them popular, but the yellow fades to brown or blue-grey with age and the fish reaches 45cm. It is solitary and feeds mainly on algae with foraminiferans, sponges, polychaetes and crustaceans. Keep at 22-26C, pH 8.1-8.4 and SG 1.020-1.025 in a tank of 950L or more. Under severe stress it releases ostracitoxin (pahutoxin) from its mucus, which can kill fish in a closed tank within a short time, so avoid shipping stress, netting and aggressive tankmates and keep it alone. It eats slowly; offer bite-sized food in several small feedings. It picks at tube worms and is not suited to reef tanks. Captive breeding has rarely succeeded. IUCN: Least Concern.
Source: Wikipedia (CC BY-SA 4.0)
The Yellow Boxfish grows to Up to 45cm.
The ideal temperature for the Yellow Boxfish is 22〜26℃.
Origin
Indo-Pacific (Red Sea and East Africa to Hawaii, north to the Ryukyu Islands)
Size
Up to 45cm
Temperature
22〜26℃
Sources: LiveAquaria / FishBase
Edited & verified by: BreederDirect editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Sources: CITES Appendices (species not listed) / IUCN Red List
Regulations may change. Always verify the latest information with the relevant authorities.
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Frozen brine shrimp, mysis, chopped clam and shrimp, seaweed
Releases ostracitoxin (pahutoxin) under stress and kills tankmates. The juvenile colour fades with growth and it reaches 45cm.
950L or more, kept alone, with carbon and a skimmer always running. Move it in a container, never a net.
22-26C, pH 8.1-8.4, SG 1.020-1.025. Avoid sudden changes.
Frozen brine shrimp, mysis, chopped clam and shrimp, and seaweed in small frequent feedings. A slow eater.
No conspecifics or aggressive fish, and no fast food thieves. Picks at tube worms, so not for reef tanks.
Advanced. This is an advanced-level species. It requires specialized equipment and advanced husbandry skills with precise environmental control.
The ideal temperature for Yellow Boxfish is 22〜26℃. Avoid sudden temperature changes and maintain a stable environment.
Yellow Boxfish typically reaches Up to 45cm as an adult. Size may vary depending on care conditions and individual genetics.
Yellow Boxfish feeds on: Frozen brine shrimp, mysis, chopped clam and shrimp, seaweed. Aim for a balanced diet with appropriate feeding frequency.
The price of Yellow Boxfish varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.
Last updated: September 15, 2026