The mesophotic coral ecosystems along Australia’s Great Barrier Reef have been revealing some exciting discoveries in recent years. Thanks primarily to the efforts of aquarium collectors like Cairns Marine, there have been several species found which proved to be new to science—Bodianus bennetti, Plectranthias bennetti, Cirrhilabrus squirei. Some important distributional expansions have been reported—Centropyge abei, Luzonichthys seaveri. And several still undescribed species are yet awaiting study—Pseudanthias cf aurulentus, Pseudanthias cf flavicauda, Prognathodes cf basabei.

A sensational series of videos, filmed by researcher Tiffany Sih using baited cameras deployed to depths of 50-300 meters, is shining a spotlight on this rarely observed fauna. Featured here are reef fishes which likely represent undescribed species, as well as a few which had previously been undocumented from the South Pacific. For the full list, check out her open access publication here, and be sure to click the “Caught on camera” link in the Electronic Supplementary Materials at the bottom to view the full video.

Highlights from this study include our first look at a beautiful, shiny blue Chromis with a black spot on its caudal peduncle. Expect this to be described in the near future. There’s a brief glimpse at a red-banded perchlet along the bottom which is thought to be an undescribed relative of the Hawaiian Plectranthias kelloggi and the Japanese P. azumanus. Expect this one to get a name soon too.

At the 1:40 mark in the above video, you’ll catch a red-streaked fish swim across the screen just below the text; this is a species from the small and rarely discussed genus Selenanthias. Precisely which species remains a mystery, as it might be undescribed or, perhaps, a female of Selenanthias barroi, known only from the nearby Chesterfield Islands and apparently a fish which has never been photographed, either alive or dead.

The Okinawa Chromis (C. okomurai) makes its South Pacific debut, as the species had previously been known only from the deep reefs of Japan. Similarly, the Japanese Chromis (C. mirationis), seen in the above video, and the Gold-rim Chromis (C. circumaurea) are two species reported for the first time from the Great Barrier Reef. And some fishes had their depth range expanded dramatically, like the Candy Hogfish (Bodianus bimaculatus, at 106 meters!), the Koran Angelfish (Pomacanthus semicirculatus, at 105 meters!), and the Yellow Fangblenny (Meiacanthus luteus, at 100 meters!).

But the icing on this piscine cake has to be the incredible terminal males of the Rose-band Fairy Wrasse (Cirrhilabrus roseafascia), which are practically swarming in front of the camera down at a depth of 155 meters! In situ images of this fish have become increasingly common thanks to several Japanese divers who operate in the Philippines, but, to my knowledge, this is the first video of this fish in its natural habitat. Its gaudy colors feel ablaze when seen against the perpetual twilight of its bleak surroundings. Truly, this has to be considered one our planet’s most singularly beautiful creatures—a species well-deserving of a David Attenborough narration.

• Sih, T.L., Cappo, M. and Kingsford, M., 2017. Deep-reef fish assemblages of the Great Barrier Reef shelf-break (Australia). Scientific reports, 7(1), p.10886.