News / Species Spotlight / Kiri Triggerfish (Xanthichthys greenei) (01/23/19)

Kiri Triggerfish (Xanthichthys greenei)

Kiri Triggerfish (Xanthichthys greenei)
Triggerfishes are large, charismatic (and tasty) members of coral reef ecosystems. They tend to get noticed by divers, researchers, and fishermen and are usually quite easily collected, which is why most species from this family were discovered and named many decades (or centuries) ago. However, in 2013, aquarists and ichthyologists alike were pleasantly surprised by the unexpected description of a beautiful new species, Xanthichthys greenei.

Specimens of this curiously spotted balistid had been seen on rare occasion in aquarium exports originating from the remote Pacific island of Kiritimati (pronounced like Christmas). This fish had been tentatively identified by the collectors as some sort of hybrid, while also at times being christened with various improper nomenclatures (e.g. X. dorsopunctatus, X. kiritimati). It wasnt until 2005 that specimens were finally collected from the wild during an expedition by the prolific deep reef explorers Brian Greene, Richard Pyle, and John Earle.

At roughly 300 feet (90-100 meters) deep, just beneath a thermocline that dropped the ambient temperature to below 70 degrees, Brian Greene managed to chase one of the swarming triggerfishes found there into a rock and collected it with his bare hands. In the process, the displeased fish managed to remove a small chunk of Brians index finger, and, without any collecting gear at hand, the unruly balistid had to be brought to the surface during a long decompression dive tucked tightly within a pocket. For his troubles, Xanthichthys greenei honors the brave hand of the ichthyologist that first collected it from the wild.

To date, the species is only known from this one location, and aquarium specimens are still a rarity. Its unclear what the full geographic extent of the Kiri Triggerfish is, as all others in its genus tend to be widely distributed in the Indo-Pacific or Atlantic. In recent years, a considerable amount of exploration has taken place at the deep reefs of Micronesia without any evidence of X. greenei being present, so its possible that this species is instead an endemic of Polynesia. Still, its never been reported from any of the well-studied reefs to the south or west (e.g. Rarotonga, Tahiti, Gambier, Kanton), giving this fish a real air of mystery about it.

But aside from its beauty and rarity, the Kiri Triggerfish is also highly recommendable as an aquarium species, especially so for those looking to keep a balistid within a reef tank. The largest measured specimen tipped the scales at just 6 inches long, and, as the fishes of this genus are largely zooplanktivores, they have a long and proven track record of leaving corals alone. Since this species originates in relatively cool waters, specimens require heavy feeding on a mixed diet of meaty foods to maintain a healthy weight in captivity, and excessively warm conditions should be avoided as much as possible.