Helmet Cowfish

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Species group:

Other common names: Camel Cowfish, Thornbacked Boxfish, Hovercraft Boxfish, Humpback Turretfish

Scientific name: Tetrosomous gibbosus

The basics:
The Helmet Cowfish shares the droll mannerisms, “rowing” swimming style and unique, “expressive” face of its relatives, and youngsters can be hard to resist. However, although pets fare well under proper care, it grows quite large and has very strict care requirements.

The huge range extends from the shores of eastern Africa through the Indo-Pacific to Indonesia, Australia, and Japan, with an introduced population, courtesy of the Suez Canal, in the Mediterranean. Typical habitats include rocky ledges, coral reefs, and seagrass beds.

Appearance / health:
The rigid, “armored” body is triangular in outline and topped by a high, pointed dorsal crest and bearing, in young animals, sharp spines along its edges. Blue and black blotches and lines mark the tan to gray body, and the large, expressive eyes are blue. Adults reach a very impressive 30 cm (12 in) in length.

Cowfish have a tendency to take in dangerous amounts of air when fed at the surface, and are also prone to becoming lodged among coral and rocks. When stressed in this manner, they will release a toxin (ostracitoxin) that usually proves fatal to tank-mates. Ill individuals should be removed from the aquarium, as the toxin is also released upon death.

Behavior / temperament:
Helmet Cowfish move about by a “fluttering” motion of the fins, with no body action being involved, and are quite amusing to observe. They are voracious invertebrate predators, and will make short work of crabs, sponges, tube worms, shrimp, sea stars, and others.

The Helmet Cowfish requires a well-filtered, cycled 680 liter (180 gal) or larger aquarium that is provisioned with caves large enough to serve as shelters, as well as open swimming areas. Crevices or “dead-ends” where the fish may become lodged must be avoided. Powerful filtration is essential, and a protein skimmer is advisable.

They should not be housed with aggressive fish, lest they become stressed and “retaliate” against attacks by releasing their deadly toxin (see above).

The Helmet Cowfish should be maintained at 23.3-26.6 C (72-80 F), a specific gravity (salinity) level of 1.020-1.025, and pH 8-8.4.

Newly-acquired individuals may refuse all but live grass shrimp, bloodworms, or Mysis. In time, most pets can be weaned to non-living foods. The diet should be varied, and include live shrimp and small crabs, and chopped clams, mussels, scallops and other marine invertebrates. Fresh, frozen and dried algae are also critical to long-term health.

Breeding pairs simultaneously release eggs and sperm, and the fry float about as plankton for a time. Captive breeding is, therefore, difficult to achieve, and has not been well-studied.

Written by Frank Indiviglio

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