Yellow Boxfish

Geographic Origin and Biotope: 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 cubicus). 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.

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 Tankmates: 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 Reproduction: 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).