Helmet cowfish (Tetrosomus gibbosus) care guide

Group
Marine fish
Family
Ostraciidae (boxfishes)
Water
saltwater
Maximum size
30 cm
Temperature
24–27°C
pH
8.1–8.4
Hardness
Salinity SG 1.023–1.026
Minimum tank
600 litres
Care level
expert
Temperament
peaceful
Reef safe
with_caution

Care

Tank and decor: a large tank with open swimming space and calm tankmates. The tank size given is an estimate based on its adult size. Little is given in our sources beyond the aquarium list; the notes below are general guidance for this kind of fish. Water: the sources give no species-specific figures, so the values here are general marine aquarium guidance: 24–27 °C, pH 8.1–8.4 and specific gravity 1.023–1.026. Keep nitrate low and the water well oxygenated. Toxin warning: boxfish and cowfish can release a toxin from the skin when stressed or dying, which can kill every fish in the tank. Handle gently, ship them in their own bag and run activated carbon. Do not eat them. Identification: tan with dark speckles and brown spots at the base of the tail fin. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies). Checked October 2026.

Diet

Our sources give no diet. Boxfish pick at small invertebrates; offer a varied diet of small meaty foods and some algae.

Breeding

Not described in our sources.

Compatibility and tank mates

The list says "with caution" for reefs: boxfish may pick at invertebrates and small corals. Keep with peaceful fish that will not harass it.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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