News / Species Spotlight / Joculator Angelfish (Centropyge joculator) (10/02/18)

Joculator Angelfish (Centropyge joculator)

Species Spotlight - Joculator Angelfish (Centropyge joculator)
Aquarium rarity comes in many different flavors. Some fishes are only found at great depth... others are naturally in low abundance on the reef some are elusive to collect and, most commonly, some species only occur in a small corner of the globe. The Joculator Angelfish is an interesting case study in rarity. It has long been one of the least-available and most-expensive of the dwarf angelfishes regularly offered to aquarists, but, seeing it on its natural reefs, it would be hard to understand why.

Unlike some of the other pricey members of this group, it doesnt occur in mesophotic depths (like the Narcosis and Peppermint Angelfishes). It isnt especially difficult to catch either, compared to highly cryptic species like the Golden Angelfish or the Blackspot Angelfish. It is instead reported to be abundant and easily found in shallow waters. So why then is this fish such a rarity?

It comes down to an extremely limited geographic range in the Indo-Pacific. Unlike virtually every other species of dwarf angelfish, C. joculator occurs in just two tiny island groups in the Eastern Indian Ocean, the Cocos-Keeling Islands and Christmas Island. These sit at an important biogeographical crossroads, where the Indian and Pacific Ocean overlap. A number of interesting hybrids from a variety of different fish families can be found here, but, in general, endemic species are uncommon outside of angelfishes.

For reasons unknown, these isolated islands have produced several beautiful dwarf pomacanthids found nowhere else. For instance, there is the Tigerpyge Angelfish hybrid and the Cocopeel Angelfish, recently (and controversially) described as a new species in recent years, C. cocosensis. But C. joculator is not an especially close relative to either of these fishes. In fact, its not even one of the true Centropyge, instead being more closely related to a large group of dwarf angelfishes that includes things like the Flame Angelfish and the Flameback Angelfish.

Its closest relative is thought to be the Multicolor Angelfish (C. multicolor), which occurs broadly throughout the Central Pacific, though its not clear why the Joculator only occurs in its present isolation in the Indian Ocean. This is one of the enduring mysteries of this beautiful blue and yellow species. The species scientific name comes from the Latin for clown, in reference to the bright colors of this fish. It was, in fact, initially mistaken by its discovers as the widespread West Pacific Bicolor Angelfish (C. bicolor), which is actually a very distant relative.

Aquarium care is no different than other dwarf angelfishes. The natural diet consists of a varied mix of sponges, detritus, algae, and perhaps the occasional benthic invertebrate (e.g. worms, crustaceans). A similarly varied mix should be offered in captivity, but most any dry or frozen food will be taken readily. Fully grown specimens measure in at just 4 inches, making this a suitable inhabitant of mid-sized reef aquariums, though, as with most pomacanthids, there is a risk posed to fleshier stony corals.