Ostracion cubicum
Encounter Rate
Spotting Difficulty
Best Season
Year-round
Depth Range
1-30 meters
The yellow boxfish is one of the most adorable and instantly recognisable fish on Komodo's reefs. Juvenile yellow boxfish are particularly endearing — tiny, bright yellow cubes no bigger than a pea, covered in black polka dots, hovering above the reef with their small fins beating furiously to maintain position. As they mature, the vivid yellow fades to a dull olive-brown and the spots become less defined, but the distinctive boxy, almost cubic body shape remains throughout their life. Their rigid body is formed by a carapace of fused bony plates called ostracine, which provides excellent protection against predators but limits flexibility. When severely stressed, boxfish can release a potent toxin called ostracitoxin into the surrounding water, which is capable of killing other fish in an enclosed space. In Komodo, juvenile yellow boxfish are a favourite find at nearly every dive site, often hovering near coral heads in shallow water. Their comical swimming style — they look like tiny yellow dice struggling against the current — never fails to bring a smile, and they are among the most photographed subjects on the reef.
Average Size
Juveniles 1-3cm, adults 20-35cm
Size Range
1-45cm
Maximum Size
45cm
Omnivore feeding on algae, sponges, polychaete worms, small crustaceans, molluscs, and tunicates. Blows jets of water at the sand to uncover buried invertebrates.
The yellow boxfish is one of the most adorable and instantly recognisable fish on Komodo's reefs. Juvenile yellow boxfish are particularly endearing — tiny, bright yellow cubes no bigger than a pea, covered in black polka dots, hovering above the reef with their small fins beating furiously to maintain position. As they mature, the vivid yellow fades to a dull olive-brown and the spots become less defined, but the distinctive boxy, almost cubic body shape remains throughout their life. Their rigid body is formed by a carapace of fused bony plates called ostracine, which provides excellent protection against predators but limits flexibility. When severely stressed, boxfish can release a potent toxin called ostracitoxin into the surrounding water, which is capable of killing other fish in an enclosed space. In Komodo, juvenile yellow boxfish are a favourite find at nearly every dive site, often hovering near coral heads in shallow water. Their comical swimming style — they look like tiny yellow dice struggling against the current — never fails to bring a smile, and they are among the most photographed subjects on the reef.
This species plays an important role in the marine ecosystem of Komodo National Park. Responsible diving practices help protect these animals and their habitat for future generations.
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The bright yellow colouration of juveniles is thought to serve as a warning of their toxicity. As they grow larger and become less vulnerable to predators, the bright warning colours fade to more cryptic olive-brown adult tones.
