Swallowtail hawkfish
A hawkfish that swims above the reef, not on it.
The swallowtail hawkfish (Cyprinocirrhites polyactis), also called the lyretail hawkfish, is a marine fish in the hawkfish family Cirrhitidae. It lives on tropical reefs in the Indian Ocean and western Pacific Ocean, and grows up to 15 cm (5.9 in) long. This species is also sold in the aquarium trade. It is the only member of its genus.
The fish was first scientifically described in 1874 by Dutch ichthyologist Pieter Bleeker, who named it *Cirrhitichthys polyactis* based on a specimen from Ambon Island. In 1917, Japanese ichthyologist Shigeho Tanaka described a new species, *Cyprinocirrhites ui*, placing it in a new genus that was later recognized as a synonym of Bleeker’s species, though the monotypic genus was kept. The genus name combines *cyprinus* (meaning “carp” or “minnow”—Tanaka did not explain why) with *cirrhites*, an alternate spelling of the type genus *Cirrhitus*. The species name *polyactis* means “many rayed,” referring to its high number of soft rays in the dorsal fin, more than any other hawkfish.
The swallowtail hawkfish stands out from all other hawkfishes in two ways: its lunate (crescent-shaped) tail fin with both upper and lower lobes elongated, and its high count of soft rays in the dorsal fin. The dorsal fin has 10 spines, each tipped with numerous cirri, and 16–17 soft rays, with the first ray elongated. The anal fin has 3 spines and 6–7 soft rays. The tail fin is lunate, with the topmost ray of the upper lobe and the bottommost ray of the lower lobe extending into filaments. The lower rays of the pectoral fin are longer than the others. Maximum total length is 15 cm (5.9 in). Its overall color ranges from orange to brownish-orange, often with orange-red to brownish blotches.
This species is found in the Indo-Pacific, from South Africa and Kenya east through the Indian Ocean to Palau, Melanesia, and Fiji, north to Japan, and south to Australia. In Australia, it occurs off Western Australia and along the Great Barrier Reef in Queensland, south to southern New South Wales. It lives at depths of 10 to 132 m (33 to 433 ft), on steep slopes and small coral heads exposed to currents.
Unlike most hawkfishes, which stay near the bottom, the swallowtail hawkfish hovers several meters above the substrate in the water column. It feeds mainly on pelagic crustaceans, copepods, and other zooplankton.
Quick Facts
- Taxon
- Cyprinocirrhites polyactis
Facts from the source article.
Lore & Background
The swallowtail hawkfish was first formally described in 1874 by Dutch ichthyologist Pieter Bleeker as Cirrhitichthys polyactis, with the type locality given as Ambon Island. In 1917, Japanese ichthyologist Shigeho Tanaka described a new species, Cyprinocirrhites ui, placing it in a new monotypic genus; this was later considered a synonym of Cirrhitichthys polyactis, but the monotypic genus was retained. The genus name combines cyprinus (meaning 'carp' or 'minnow') and cirrhites (an alternative spelling of Cirrhitus), while the specific name polyactis means 'many rayed', referring to its high dorsal fin soft ray count, higher than any other hawkfish.
This species differs from all other members of the family Cirrhitidae in two features: its lunate caudal fin with both upper and lower lobes elongated, and its high dorsal fin soft ray count. The dorsal fin has 10 spines, each with numerous cirri at its tip, and 16–17 soft rays, the first ray being elongated. The anal fin has 3 spines and 6–7 soft rays. The lower pectoral fin rays are longer than the others. The overall color is orange to brownish-orange, frequently with orange-red to brownish blotches.
Unlike other hawkfishes, which are mostly benthic, the swallowtail hawkfish stays in the water column several meters above the substrate. It preys largely on pelagic crustaceans, copepods, and other zooplankton. It may be a protogynous hermaphrodite, but further study is needed to confirm this.
Reader's Guide
The swallowtail hawkfish is significant as the only known member of its genus, Cyprinocirrhites, and for its unique morphological traits that set it apart from all other hawkfishes. Its lunate caudal fin with elongated lobes and high dorsal fin soft ray count are diagnostic features. Ecologically, it is notable for its pelagic behavior, hovering in the water column above the reef rather than staying on the substrate like most hawkfishes. This species is found on tropical reefs in the Indian Ocean and western Pacific Ocean, at depths between 10 and 132 meters, inhabiting steep slopes and small coral heads exposed to current. It is occasionally found in the aquarium trade. The species was first described in 1874 by Pieter Bleeker, and later a monotypic genus was created by Shigeho Tanaka in 1917, though the original species name was retained. Its diet consists of pelagic crustaceans, copepods, and other zooplankton. The possibility that it is a protogynous hermaphrodite remains unconfirmed and requires further study.
Frequently Asked Questions
What is the Swallowtail hawkfish?
The Swallowtail hawkfish (Cyprinocirrhites polyactis), also known as the lyretail hawkfish, is a small reef-dwelling marine fish in the hawkfish family Cirrhitidae. It is the only species placed in the genus Cyprinocirrhites, making it a one-of-a-kind member of that particular lineage.
Where does the Swallowtail hawkfish live in the wild?
You'll find it patrolling tropical coral reefs across the Indian Ocean and western Pacific, with its range stretching from South Africa and Kenya eastward to Japan, Australia, and Fiji. It occupies a notably wide depth band, from roughly 10 meters down to about 132 meters (33–433 ft).
How big does the Swallowtail hawkfish get?
Adults top out at around 15 centimeters (about 6 inches) in total length, which places it in the smaller end of the hawkfish family. Its compact size makes it a manageable option for reef-keeping setups.
What is the Swallowtail hawkfish's behavior on the reef?
Unlike many hawkfish that perch on the reef itself, this species is noted for swimming above the reef structure rather than sitting on it. That free-swimming habit sets it apart behaviorally from its more sedentary relatives.
Who first described the Swallowtail hawkfish and when?
Dutch ichthyologist Pieter Bleeker gave it its original scientific description in 1874, basing the name on a specimen collected from Ambon Island. A later 1917 paper by Japanese ichthyologist Shigeho Tanaka introduced a closely related name that eventually led to the current genus placement.
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