Yellow Boxfish
Ostracion cubicum
The Toxic Yellow Dice (18 inches / 45 cm). The Yellow Boxfish is overwhelmingly cute as a baby: it looks exactly like a perfect, hovering, bright yellow dice with black polka dots. Sadly, it is sold constantly to ignorant beginners who have no idea they just bought a massive, highly toxic biological weapon. Its body is actually a solid, rigid bone-box (like a turtle shell), making it incredibly clumsy. If frightened or killed, it can literally 'nuke' and wipe out your entire aquarium in minutes.
Température de l’eau
24 - 27 °C
Valeur du pH
8.1 - 8.4
Type d'eau
Marin
Niveau dans le bac
Fond et milieu
Taille adulte
45 cm
Volume minimal du bac
>= 500 L
Groupe minimal
>= 1
KH
7 - 15 dKH
Description de l'espèce
Geographical Origin and Habitat: Indo-Pacific Ocean and Red Sea. Inhabits protected coastal lagoons, mangrove forests and reef areas sheltered from strong currents.
Taxonomy and Morphology: Yellow Boxfish (Ostracion cubicum). Boxfish. The body is literally a rigid bone carapace in the shape of a cube. Only eyes, tubular mouth, fins and tail emerge from this immobile "armor".
Social Behavior: A clumsy helicopter. Does not flex its body to swim (it cannot), but uses its tiny pectoral, dorsal and anal fins as propellers (ostraciiform swimming) to hover metrically over corals.
Coloration and Sexual Dimorphism: Total transformation. Juveniles (beloved by aquarists) are perfect dice, bright lemon yellow covered in black polka dots (like a pac-man). Adults (gigantic) elongate and become blue-brown/dirty mustard losing much of their charm.
Soins, reproduction et cohabitation
Aquarium Setup: Extreme Marine by size (minimum 150-200 cm / 60-80 inches for the 45 cm / 18 inches adult). No violent wavemakers: its clumsiness would make it crash continuously or stick to the suction grilles. Flat rockwork.
Diet and Feeding: Omnivorous scraper. Scrapes ascidians, sponges, algae, worms and crustaceans from the substrate. It needs an abundant and very frequent diet in the tank: nori algae, mysis, clam meat. If it wastes away, the "box" belly will recede (sunken belly).
Water Quality: Lethal stress for the whole tank. Any chemical fluctuation will stress it. Being without true defensive scales, it is sensitive to copper-based medications (use hyposalinity).
Compatibility and Cohabitation: Highly not recommended in Reefs. Nibbles on SPS, LPS, giant clams and sponges. Must be kept in "Fish-only" tanks with peaceful and slow companions (Seahorses, Pipefish) as fast fish would steal all its food.
Aquarium Breeding: Totally absent in captivity. Releases pelagic eggs in the open sea. Too big, slow and aggressive towards conspecifics to form domestic pairs.
Risks and Diseases: The Doomsday Weapon (Ostracitoxin). Under the skin, the boxfish possesses glands that secrete a lethal, foamy poison. If it is bullied by another fish or the pump breaks causing it extreme stress, it will release ostracitoxin into the water, killing (often in 10 minutes) EVERY fish in the aquarium, including itself (Nuke the tank).
Origine et répartition géographiques
Indo-Pacific Ocean and Red Sea. Inhabits protected coastal lagoons, mangrove forests and reef areas sheltered from strong currents.
Origine
Océans tropicaux et récifsAmérique du Nord
Profil de poisson
- Tempérament
- Semi-aggressive
- They are curious, peaceful, and personable fish that often beg for food. However, if severely stressed or dying, they can release a potent toxin (ostracitoxin) that can wipe out the entire aquarium. It is vital to maintain a stress-free environment for them.
- Régime alimentaire
- Omnivore
- They are omnivorous and require a highly varied diet. Offer marine algae, spirulina, mysis shrimp, and chopped meaty foods. Because of their small mouths, food must be finely chopped or naturally small.
- Espérance de vie
- 5-15 years
- Taille adulte
- 45 cm
- Ratio des sexes
- Flexible
- Juveniles are bright yellow with black spots, but males become brownish-blue with faded spots as they age. They are highly aggressive toward other Boxfish. It is strictly recommended to keep only one per aquarium.
- Fréquence d'alimentation
- Twice daily
- They should be fed small amounts two to three times daily. Their unique body shape makes swimming difficult, so they need frequent energy top-ups. Ensure they are actually swallowing the food and not just spitting it out.
- Charge biologique
- High
- The Yellow Boxfish produces a moderate bioload that increases significantly as they grow. They are messy eaters and can reach an impressive size. A powerful protein skimmer and frequent water changes are essential.
- Courant
- Moderate
- Ostracion cubicum needs steady, moderate circulation distributed across the aquarium rather than a narrow, forceful jet. Extreme Marine by size (minimum 150-200 cm / 60-80 inches for the 45 cm / 18 inches adult). No violent wavemakers: its clumsiness would make it crash continuously or stick to the suction grilles. This preserves useful water exchange while retaining calmer shelter for rest and feeding.
- Risque de saut
- No
- Reproduction
- Oviparous
- Breeding Boxfish in a home aquarium is undocumented and extremely difficult. They are pelagic spawners that release eggs into the open ocean. Replicating the necessary environment and rearing the fry is currently impossible for hobbyists.
- Compatibilité et compagnons
- Peaceful
- They are peaceful and should only be kept with other very peaceful fish. They are slow swimmers and easily outcompeted for food by aggressive tank mates. Use caution in reef tanks, as they may occasionally nip at tube worms or small corals.
- Niveau dans le bac
- Middle/Bottom
- They spend most of their time hovering in the middle and lower levels of the tank. They are curious and will carefully inspect live rock for tiny crustaceans. They rarely swim at the very surface.
Modèles et paramètres scientifiques
FishBase
Fenêtre sur les données scientifiques officielles de l’espèce
FishBase v25.04Données synchronisées le : 15/06/2026
- Niveau trophique
- 3,3 ± 0,35 se
- Résilience
- Élevée (moins de 15 mois)
- Singularité phylogénétique (PD50)
- 0.502
- Relation bayésienne longueur-poids
- a = 0.05495, b = 2.75
- VulnérabilitéVulnérabilité faible à modérée (35 / 100)
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