Hawkfish

Hawkfish
Stocky hawkfish, Cirrhitus pinnulatus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Cirrhitidae
Genera
Amblycirrhitus Cirrhitichthys Cirrhitops Cirrhitus Cristacirrhitus Cyprinocirrhites Isocirrhitus Itycirrhitus Neocirrhites Notocirrhitus Oxycirrhites Paracirrhites

Hawkfish are strictly tropical, perciform marine fish of the family Cirrhitidae. Associated with the coral reefs of the western and eastern Atlantic and Indo-Pacific, the hawkfish family contains 12 genera and 32 species. They share many morphological features with the scorpionfish of the family Scorpaenidae.

Hawkfish have large heads with thick, somewhat elongate bodies. Their dorsal fins are merged, with the first consisting of ten connected spines. At the tip of each spine are several trailing filaments, hence the family name Cirrhitidae, from the Latin cirrus meaning "fringe." Their tail fins are rounded and truncate and their pectoral fins are enlarged and skinless. Their scales may be cycloid or ctenoid. Most hawkfish are small, from about 7-15 centimetres in length. The largest species, the giant hawkfish (Cirrhitus rivulatus) attains a length of 60 centimetres and a weight of 4 kilograms. A commercial fishery exists for the larger species as they are considered excellent food fishes.

The vibrant colours exhibited by most hawkfish have won them popularity in the aquarium hobby, aided by the fishes' reputation for unproblematic upkeep and easy acclimation to tank life. Popularly kept species include the longnose hawkfish (Oxycirrhites typus), coloured in a red and pink crosshatch pattern, and the flame hawkfish (Neocirrhites armatus).

Perched Freckled hawkfish (Paracirrhites forsteri) from East Timor

Thanks to their large, skinless pectoral fins, hawkfish are able to perch upon fire corals without incurring harm. Actually hydrozoans rather than true corals, fire corals possess stinging cells called nematocysts which would normally prevent close contact. Afforded some degree of protection by their living perches, hawkfish seek the high ground of the reef where they warily survey their surroundings; redolent of a hawk's behaviour, this habit inspired their common name.

Most hawkfish are solitary in nature but some will form pairs and share a head of coral. Other species form harems of up to seven females dominated by a larger male. They are diurnal and remain within the shallows of the reef, no deeper than 30 metres. Typically motionless, hawkfish will dart out to grab crustaceans and other small invertebrates which happen to pass by.

Spawning occurs at night, at or near the water's surface. Hawkfish are pelagic spawners; that is, they release many tiny buoyant eggs which drift with the ocean currents until hatching. Hatching is thought to happen after about three weeks; the distance travelled in this time may explain the exceptionally wide distribution of hawkfish. They have not been successfully bred in the aquarium, with the exception of the longnose hawkfish.

Hawkfish are noted for their protogynous hermaphrodism: functional females will change into males if the dominant supermale dies. Hawkfish are generally not sexually dichromatic, meaning the sexes cannot be distinguished by coloration alone.

Gallery

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  Black-sided hawkfish (Paracirrhites forsteri)

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  Dwarf hawkfish (Cirrhitichthys falco), Sipadan, Malaysia

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  Long-nose Hawkfish (Oxycirrhites typus), Galapagos Islands

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  Coral Hawkfish (Cirrhitichthys oxycephalus), Galapagos Islands

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  Black-sided Hawkfish (Paracirrhites forsteri), Kona, Hawaii

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  Arc-eye Hawkfish (Paracirrhites arcatus), Kona, Hawaii

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  Spotted hawkfish (Cirrhitichthys aprinus), Lembeh Straights, Indonesia

References

• Froese, Rainer, and Daniel Pauly, eds. (2005). "Cirrhitidae" in FishBase. July 2005 version.