The Deepwater triggerfish, Rhinecanthus abyssus, is the rarest species of a genus of otherwise very common triggerfish. After years of covering rare fish and especially every triggerfish, the first living example of this fish has just turned up in Thailand as photographed by our friend, Ohm Pavaphon.
Commonly called picasso triggerfish, the name is used loosely for many of the Rhinecanthus triggerfish but mostly for ‘the’ picasso triggerfish, R. aculeatus which is widespread across the Indo-Pacific. Like so many other so-called Holy Grail triggerfish before it like the Goldenback triggerfish & Linespot triggerfish, the reason for the Abyssal triggerfish being virtually unknown is due to its preference for extremely deep water.
Deep is literally in the name of Rhinecanthus abyssus which was actually discovered by a few examples that were actually caught on hook & line and brought up from 150 meters deep, or just shy of 500 feet. Since its original description in 1989 the Deepwater triggerfish has gone virtually unseen until this one specimen was caught in Indonesia.
Left to right: Rhinecanthus lunula, R. abyssus, R. cinereus.
One reason that the R. abyssus triggerfish is also unknown is that it bares a very similar resemblance to two other rare triggerfish, Rhinecanthus lunula from the South Pacific and R. cinereus from Mauritius. The difference is subtle but noticeable upon inspection with slight deviations in the color and pattern of the eye stripe, ‘jaw’ stripe, body color, tail stripe and the color of the tail.
As far as triggerfish go, the deepwater triggerfish is very neat, but it certainly isn’t a looker and you could make the case that of all the ‘Picasso’ triggerfish, Rhinecanthus abyssus is the least colorful. Nevertheless, the interest in Picasso triggers including the rare lunula and cinereus goes beyond looks as these fish are generally personable, have a unique appearance, and make great aquarium fish.
