Longhorn cowfish

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Longhorn cowfish
Lactoria cornuta.002 - Aquarium Finisterrae.JPG
A longhorn cowfish in Aquarium Finisterrae (Spain)
Haeckel Ostraciontes.jpg
Several boxfish, including the longhorn cowfish.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Tetraodontiformes
Family: Ostraciidae
Genus: Lactoria
Species: L. cornuta
Binomial name
Lactoria cornuta
(Linnaeus, 1758)

The longhorn cowfish, Lactoria cornuta, is a variety of boxfish from the family Ostraciidae, recognizable by its long horns that protrude from the front of its head, rather like those of a cow or bull. They are a resident of the Indo-Pacific region and can grow up to 50 centimetres (20 inches) long. While badly suited to the home aquarium, the cowfish is becoming increasingly popular as a pet.

Adults are reef fish, often solitary and territorial, and live around sand or rubble bottom up to a depth of 50 m. They are omnivorous, feeding upon benthic algae, various microorganisms, and foraminiferans that it strains from sediments, sponges, polychaete worms from sand flats, mollusks, small crustaceans, and small fishes, able to feed on benthic invertebrates by blowing jets of water into the sandy substrate.


Its primary habitat is coral reefs in lagoons, on reef flats, and on protected seaward reefs. Juveniles associate with Acropora corals. Depth range is 3.3–148 ft (1–45 m, perhaps up to 100 m).


Red Sea and East Africa eastward through Indonesia to Marquesas, northward to southern Japan. Including Tuamotus, southern Korea, north to the Ryukyu Islands of southern Japan, south to Australia and Lord Howe Island, and off southern Africa in the Atlantic. Tropical and subtropical waters.

Also, found in Blue Planet aquarium Scarborough and Chester.


Appendage Number (total)
Dorsal spines 1
Dorsal soft rays 8 - 9
Anal spines 0
Anal soft rays 8 – 9
Caudal fin rays 9 - 10

There is no known sexual dimorphism, so both male and female display a yellow to olive base color, which is decorated with white or bluish spots. Paired courtship just before or after sunset. Eggs and larvae are pelagic.

One distinction from other fish is the lack of a gill cover, which is replaced by a small slit or hole. The hexagonal plate-like scales of these fish are fused together into a solid, triangular, box-like carapace, from which the fins and tail protrude. Their unique method of swimming, called ostraciform swimming, causes them to look as if they are hovering. They have no pelvic skeleton, so they lack pelvic fins. They are such slow swimmers cowfish are easily caught by hand, making a grunting noise when captured. This is the most well-known cowfish species in the aquarium trade.


If severely stressed, this species may be able to exude deadly toxin, ostracitoxin, an ichthyotoxic, hemolytic, heat-stable, non-dialyzable, non-protein poison in the mucous secretions of their skin. It is apparently unique among known fish poisons; it is toxic to boxfish and resembles red tide and sea cucumber toxins in general properties.