News / Species Spotlight / Species Spotlight - Orange Back Fairy Wrasse (Cirrhilabrus aurantidorsalis) (11/15/17)

Species Spotlight - Orange Back Fairy Wrasse (Cirrhilabrus aurantidorsalis)

Species Spotlight - Orange Back Fairy Wrasse (Cirrhilabrus aurantidorsalis)
There are quite a few examples of fairy wrasses which have especially limited distributions in the wild. Theres C. nahackyi from Fiji and Tonga. Theres the Flame Wrasse, which occurs only around Hawaii. Theres the Naoko Fairy Wrasse of Western Sumatra. But perhaps the most restricted in range is the Orange Back Fairy Wrasse, which is mostly known from just one small bay in Indonesia.

Cirrhilabrus aurantidorsalis was described from the Togean Islands of Tomini Bay, a deep inlet in the northern portions of Sulawesi. And, since being named in 1999, it has only been sighted in one other location, the Lembeh Straits, at the very northern tip of Sulawesi. Fortunately, there is some occasional aquarium collection in this area, so you will occasionally find this species offered. Despite its general uncommonness in the wild, it is abundant and easily collected within its range, meaning specimens are surprisingly affordable.

This species belongs to a closely knit group which occurs from Bali to Micronesia, including C. luteovittatus, C. randalli, and C. solorensis. Another example is the recently discovered Darwin Glow Wrasse, an undescribed species that has been collected from the waters south of Timor (and north of Darwin, Australia). A similar (and possibly identical) fish occurs further north in some of the smaller islands of Indonesia. In many ways, that fish is quite like the Orange Back Fairy Wrasse, as both develop a fairly orange back. But they can be told apart easily enough, as the true C. aurantidorsalis has a beautiful burgandy head (vs. a dingy blue-grey in the undescribed species), and the orange dorsal coloration begins just behind the head.

One unusual feature of this particular Cirrhilabrus species group is that males develop fluorescent colors visible only with ultraviolet light. This presumably serves some purpose for signaling to females and rival males. But since this phenomenon was only recently discovered, it has yet to be sufficiently studied, though it certainly helps to explain why these wrasses lack any obvious nuptial colors. Recall that most others in the genus flash bright colors with their dorsal stripes or have a reflective caudal fin.

Fairy wrasses are often associated with rubble habitats well away from the pristine coral reefs we see in coffeetable books, but the group to which C. aurantidorsalis belongs is an exception. They generally can be found in shallow habitats that are rich in SPS and soft corals.

In an aquarium, it is best to keep a single individual, or, in larger systems, it become possible to acquire a small harem. Mixing different species of Cirrhilabrus is also possible, but this can prove to be challenging when dealing with some of the larger and more aggressive members. Some good choices would include C. lubbocki, C. rubripinnis or C. bathyphilus (and any of the species related to these). These also frequently occur alongside anthias, which would make for an ideal pairing. As with all other fairy wrasses, C. aurantidorsalis is a zooplanktivore and should be fed a diverse diet of dry foods, frozen worms and crustacean, and fish eggs.