Family : Chaetodontidae
Text © Giuseppe Mazza
English translation by Mario Beltramini
Eritrean butterflyfish (Chaetodon paucifasciatus Ahl, 1923) belongs to the class of the Actinopterygii, the ray-finned fishes, to the order of the Perciformes and to the family of Chaetodontidae.
For some, it should be a subspecies of the Chaetodon madagaskariensis Ahl, 1923, along with the Chaetodon xanthurus Bleeker, 1857 and the Chaetodon mertensii – Cuvier, 1831.
The name of the genus comes from the Greek “chaite” = hair and “odous” = tooth, due to “the bristle shaped teeth”.
The species name “paucifasciatus” means, in Latin, “with few bands”.
It lives in the tropical waters of the Indian Ocean, mainly localized in the Red Sea and the Gulf of Aden.
It is common in the plain part of the madreporic formations, but it can go down also along the borders of the reefs up to about 60 m of depth.
It does not exceed the 14 cm. The body is flat, more or less squared, with the snout slightly elongated for looking for food among the corals. The dorsal fin has about 12 spiny rays and 20 soft; the anal has 3 spiny rays and about 18 soft. The ventral and the pectoral ones are unarmed. The caudal is more or less blunt.
Like Chaetodon madagaskariensis it has rigid yellow dorsal fins, the white-edged spot on the head and the black slanted traits folding backward at the height of the eye, forming parallel angle brackets, which, at the end, transform in lined small dots. The eye is not masked by a black stripe, but by a brown band, which, however, performs the same camouflaging function. Also the pattern on the caudal and the soft parts of the dorsal and anal fins is analogous to the Madagascar butterflyfish, but here it is decidedly redder with black spots.
The Chaetodon paucifasciatus nourishes of madrepores polyps, gorgonians, polychetes and small crustaceans, but also of algae, and it’s thanks to this varied diet that it resists better than other species to the degradation of the reefs connected with the climate changes, with an incredibly low vulnerability index of 12 per 100. In fact, excluding the aquaria trade, it is not fished for alimentary purposes and the populations can double in less than 15 months
It lives in small schools, very often paired. After having spawned and fecundated the eggs, abandoned to the currents, the parents, usually, do not separate.
Chaetodon chrysurus paucifasciatus Ahl, 1923.