Chaetodon ornatissimus, commonly known as ‘ornate butterflyfish‘, is a species of fish in the family Chaetodontidae. The genus name ‘Chaetodon‘ comes from the Greek words ‘chaite‘ (hair) and ‘odous‘ (tooth), referring to the fine, bristle-like teeth these fish possess. The epithet ‘ornatissimus‘ is derived from Latin and means ‘very ornate‘ or ‘the most ornate‘, which perfectly describes its colorful and complex pattern. This butterflyfish is found in the Indian and Pacific Oceans, from the coasts of East Africa to the Hawaiian, Marquesas and Ducie Islands, and from southern Japan to the Great Barrier Reef in Australia. It mainly inhabits coral reefs and coastal lagoons at depths between 1 and 30 meters.
Chaetodon ornatissimus is a medium-sized fish that can grow to approximately 20 centimeters in length. Its body is flattened laterally and has a high profile, typical of butterfly fish. Its coloration is predominantly white, with a pattern of diagonal bands in shades of orange-yellow crossing the body. Four prominent vertical black bars cross the head: one passes across the snout, one across the eye, acting as camouflage against predators, and two others lie between the band across the eye and the gills. The third of the black stripes on the head continues along its long, continuous dorsal fin, flanked at the edge with a yellow perimeter stripe. The anal fin, which is also elongated, also has a black horizontal stripe bordered by a yellow line. The caudal fin is white with three vertical stripes, the most anterior and posterior one black, and the central one yellow. Chaetodon ornatissimus can be easily confused with similar species such as Chaetodon lunulatus or Chaetodon meyeri, but is differentiated by its unique pattern of diagonal stripes and the arrangement of the facial bars.
In terms of its feeding habits, Chaetodon ornatissimus is primarily a specialized feeder of coral polyps, especially hard corals. It uses its small, protruding mouth, equipped with bristle-like teeth, to extract polyps from coral colonies. Although its diet consists mainly of coral polyps, it may also consume small invertebrates, such as worms and crustaceans, as well as algae. This feeding preference makes this species vulnerable to coral reef degradation, as it is highly dependent on the availability of coral polyps as a food source.
Reproduction of Chaetodon ornatissimus is oviparous and usually occurs during the warmer months when reef conditions are more favorable. During the mating season, individuals form monogamous pairs. Courtship involves a series of complex behaviors, including synchronized swimming and dancing. After courtship, the female releases the eggs into the water column, where they are fertilized by the male. The eggs are pelagic, float in the water and hatch after several days, releasing larvae that develop in the water column before settling on the reefs as juveniles.
A curiosity about Chaetodon ornatissimus is its high fidelity to the territory and to its mate. This species is often observed in pairs, even outside the breeding season, indicating long-term monogamous behavior. In addition, due to its specialized diet, Chaetodon ornatissimus may be an indicator species for coral reef health, as its presence and abundance are closely related to the availability of live coral.
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