The Yellow Crown Butterflyfish, Chaetodon flavocoronatus, is a true rarity. It’s a close relative of the Hawaiian or Tinker’s Butterflyfish, Chaetodon tinkeri, featured in the current May/June 2025 issue of CORAL Magazine. These species, along with a couple of other relatives (C. burgessi, C . declevis, and C. mitratus), have the distinction of being rather agreeable aquarium residents who may, at times, be considered at least somewhat reef-safe. Not everyone agrees with that assessment. So, not always reef safe, mind you, but certainly not the harbingers of doom that most Chaetodontids represent in a reef aquarium. Given their deepwater preferences, none of these species are plentiful in the trade, and when they are encountered, they are priced accordingly.

But ultimately, were it not for the general ongoing prohibition of marine fish collection in the waters of Hawaii, the Yellow Crown Butterflyfish was, and probably still is, the least-encountered member of the Roaops subgenus. Which brings us to this incredible video of the species captured by ROV footage by the E/V Nautilus during an expedition to the Ahyi Seamount.

Capturing and sharing this type of footage is part of the greater missiong of the Ocean Exploration Trust, which was “Founded in 2007 by Titanic discoverer Dr. Robert Ballard, Ocean Exploration Trust’s international expeditions launched from aboard Exploration Vessel Nautilus center scientific exploration of the seafloor, collaborating with the broad scientific and local communities, and engaging curious minds worldwide via interactive live streaming deep sea exploration and education programs.” You can watch live streaming footage at https://nautiluslive.org/

Before we get to the video, though, it’s worth mentioning that the Crosshatch Triggerfish, Xanthichthys mento, also makes a cameo appearance during the video. However, the observers commenting on the video fail to mention something else. I (CORAL Editor and Publisher Matt Pedersen) watched this video and nearly “lost my mind” when I noticed an even lesser-known species that briefly enters the frame.

The video shares a brief glimpse of a male Spotted Angelfish, Genicanthus takeuchii. This species has likely never entered the aquarium trade, and this encounter at Ahyi Seamount might even represent a range extension. Efforts to document these hidden ocean depths reveal unknown surprises and are well worth the investment.

Watch the stunning footage of Chaetodon flavocoronatus on the mesophotic reefs of the Ahyi Seamount, now!