All fish / Ostraciidae

Yellow Boxfish

Ostracion cubicus

Also known as yellow boxfish, cube boxfish, polka dot boxfish, spotted boxfish, yellow cubefish, cowfish, boxfish, caution, ปลาปักเป้ากล่องเหลือง, ikan buntal kotak, ミナミハコフグ, ikan buntal kotak kuning

Juveniles are bright yellow cubes with black spots, fading to a duller yellow-brown or bluish adult with smaller spots and a longer body. Its boxy bony armour, hovering swim and inquisitive, pet-like manner make it a popular fish-only marine showpiece.

Care at a glance

Care level

Hard

Temperament

Semi

Adult size

30 cm

Temperature

24 to 28 °C

pH

8.1 to 8.4

Smallest tank

700 litres

Keep as

Keep singly

Diet

Omnivore: mysis, krill, chopped clam and squid, marine algae and nori, quality marine pellets

Swims

Middle of the tank

Lifespan

5 to 10 years

Water

Marine (saltwater)

Wild range

Indo-Pacific and Red Sea, from East Africa to Hawaii and southern Japan to Australia

Breeding

Pairs spawn in open water at dusk after the male courts the female, and the eggs and larvae drift with the plankton. It has not been bred reliably in home aquariums.

Good to know

When stressed, dying or harassed it can release ostracitoxin, a skin toxin that can kill everything in the tank, so use a large tank with good skimming and carbon, and avoid nippy tankmates. The tiny juveniles sold grow into large adults that are not reef safe and will pick at invertebrates.