News / Species Spotlight / Yellow Flanked Fairy Wrasse (Cirrhilabrus cyanopleura) (05/30/18)

Yellow Flanked Fairy Wrasse (Cirrhilabrus cyanopleura)

Species Spotlight - Yellow Flanked Fairy Wrasse (Cirrhilabrus cyanopleura)
Among fairy wrasses, Cirrhilabrus cyanopleura is one of the most commonly seen and affordable options. The species occurs across much of the West Pacific, from Japan to Australia and the Solomon Islands. It even occurs in the Andaman Sea, though, strangely, this fish is seemingly absent from places like Vanuatu, New Caledonia, and Fiji, where it would otherwise be expected. Why this is so is something of a mystery.

Throughout its range, C. cyanopleura occurs in relatively shallow habitats that are often rich in stony coral growth. This is in stark contrast to many of the other members in this genus, which tend to occur in the deep, rubble slopes that fringe reef systems. The typical habitat for this species is amongst large fields of branching corals, often alongside various anthias and damselfishes. You will, however, still see this fish in rubble zones, and even near seagrasses on occasion.

One of the enduring mysteries of C. cyanopleura is its yellow-flanked form, which occurs only in the Philippines and north into the Japan. This is usually the dominant form here, though the large shoals formed (which can easily number in the hundreds) still tend to feature a number of individuals which lack the characteristic yellow pectoral marking. But why?

It remains unknown if this is truly a distinct species, but, given its geographically restricted range, it seems plausible. The name Cirrhilabrus ryukyuensis (recently amended from C. lyukyuensis) is frequently applied to this form, and many references currently recognize it as a valid species.

As an aquarium fish, this is highly recommendable for a medium to large reef. Males can be expected to reach around 5 inches in length and feature an olive head, followed by a blue band and an orange to red back, with the belly stark white throughout. Youll sometimes see this fish confused with the closely related members of the solorensis complex, some of which are still undescribed and can look confusing similar. The main trait to distinguish them is the bluish hue found in the lower operculum and throat in the members of that group.

Females, as with most Cirrhilabrus, are mostly pink with a series of minute dots along the sides, along with a white tip to the mouth and a black spot on the caudal peduncle. These traits all disappear with age, until eventually the male coloration is attained. Its rare, however, to see females offered, as the males are considered far more desirable in this genus. Those aquarists who have experimented with keeping harems of a single species together have tended to find that, given time, all specimens turn male, which can create new and exciting behavioral problems to attend to. Males, as a rule, dont like other males. <