Family : Chaetodontidae
Text © Giuseppe Mazza
English translation by Mario Beltramini
The Saddle butterflyfish (Chaetodon ephippium Bloch & Schneider, 1801), belongs to the class of the Actinopterygii, the ray-finned fishes, to the order of the Perciformes and to the colourful family of Chaetodontidae.
The name of the genus Chaetodon comes from the Greek “khaite”, hair, and “odous”, tooth, due to the bristle-shaped teeth.
The name of the species ephippium comes from the Greek “efippion” = saddle, due to the saddle-shaped design on the back.
The Saddle butterflyfish has a very vast distribution. It lives mainly in the tropical waters of the Pacific Ocean, but also, in a lesser extent, in the Indian Ocean.
It is at home in Indonesia, Australia, New Guinea, Micronesia, New Caledonia, Philippines, Taiwan, China, up to southern Japan, and, eastwards, Vanuatu, Fiji, Tonga, Samoa, up to Hawaii islands. We then find it, in the Indian Ocean, in Malaysia and in Sri Lanka.
It visits the sunlit madreporic formations looking for filamentous seaweeds and predates the microfauna up to 30 m of depth.
With even 30 cm of length, it is one of the greatest butterflyfishes. The body is flat, almost squared, apart the head, with a pointed snout for rummaging in the crevices.
The dorsal fin, which in the adults has, like the Chaetodon auriga, a filament that can exceed the length of the tail, counts 12-14 spiny rays and 21-25 soft; the anal has 3 spiny rays and 20-23 soft. The ventral and the pectoral fins are unarmed. The caudal is more or less blunt.
The livery is unmistakable due to the huge black dorsal saddle, emphasized, downwards, by a wide white band and on the back by an orange stripe. The rest of the body is grey-yellowish, with about 6 horizontal stripes tending to blue, at times barely visible. The lower part of the head, the ventral fins and the lower margin of the anal one has a nice bright yellow colour.
Also the tail, translucent, ends in a yellow small border, preceded by an orange peduncle which resumes the colour of the band present on the dorsal and on the anal. The eye is camouflaged by the usual vertical black stripe, which, however, in this species, does not cross the whole body, and after the operculum we see another black trait.
The saddle butterflyfish is active day and night. It swims solitary, in pair or in small schools looking for filamentous seaweeds, polyps of coral, small crustaceans, polychaetas and eggs of other fishes.
The reproduction does not take place in group, but in pairs with pelagic eggs.
Even if predated by the aquaria lovers, it has a modest fishing vulnerability index, just 20 on a scale of 100, because anything goes, thus reacting better than other species to the environmental changes, with populations which may double in less than 15 months.
Chaetodon garnoti Lesson, 1831; Chaetodon mulsanti Thiollière, 1857; Chaetodon principalis Cuvier, 1829.