Tetrasomus gibbosus - Hovercraft Cowfish

The Hovercraft Cowfish belongs to the boxfish family Ostraciidae. Most of its body is enclosed inside a rigid carapace formed from fused bony plates. The eyes, mouth, gills and fins extend through openings in the protective structure.

Its movement is produced mainly by the pectoral, dorsal and anal fins, creating the controlled hovering motion responsible for the common name.

Key features

• Distinctive armoured marine boxfish
• Scientific name: Tetrosomus gibbosus
• Common name: Hovercraft Cowfish
• Also known as Humpback Turretfish and Camel Cowfish
• Triangular body profile
• Prominent dorsal hump
• Controlled hovering swimming style
• Bright yellow or orange when young
• Adult coloration becomes more subdued
• Adult size commonly around 20 cm
• Maximum size approximately 30 cm
• Generally peaceful but demanding
• Omnivorous diet
• Requires several small meals daily
• Not recommended for reef aquariums
• May consume corals and invertebrates
• May release ostracitoxin when severely stressed
• Requires a large, established marine aquarium
• Recommended only for experienced marine aquarists

Care information

• Adult size: commonly around 20 cm, up to approximately 30 cm
• Diet: omnivore
• Temperament: peaceful and generally solitary
• Reef compatibility: not recommended
• Care level: advanced
• Origin: Indo-West Pacific
• Natural habitat: muddy and sandy bottoms, seagrass beds and reef margins

Suggested water conditions

• Temperature: approximately 23–27 °C
• Specific gravity: approximately 1.020–1.025
• pH: approximately 8.1–8.4
• Alkalinity: approximately 8–12 dKH
• Ammonia: 0 mg/l
• Nitrite: 0 mg/l
• Flow: low to moderate
• Oxygenation: high

Recommended aquarium

• Long-term minimum volume: approximately 500–600 litres
• Larger aquarium preferred for a full-grown specimen
• Extensive open swimming area
• Broad turning space
• Sand or fine-gravel substrate
• Rounded, stable rockwork
• Low- and moderate-flow areas
• Powerful biological filtration and protein skimming
• Fresh activated carbon available for emergencies
• Keep only one cowfish or closely related boxfish per aquarium

Feeding

Offer a varied diet including:

• Mysis shrimp
• Enriched brine shrimp
• Chopped shrimp
• Mussel
• Krill
• Squid
• Marine algae
• Spirulina foods
• High-quality sinking marine pellets
• Food paste attached to rock or aquarium glass

Feed approximately three small meals daily. Avoid floating foods because the fish may swallow air and develop buoyancy problems.

Toxin emergency

If the fish is severely injured, dies or is suspected of releasing toxin:

1. Remove the fish immediately.
2. Perform a large water change.
3. Add fresh activated carbon.
4. Increase protein skimming and aeration.
5. Transfer other fish to clean seawater if necessary.
6. Monitor all livestock for rapid breathing or abnormal swimming.
7. Replace the activated carbon again after a short treatment period.
8. Do not handle a dead specimen with bare hands.