If you’re still reading and following on our Osaka updates, then welcome to part two of four! In our previous installation we visited Mr. Makoto Matsuoka and took a look at some of his rare butterflyfish collection. This time we’re featuring another Japanese aquarist and his fish, but instead of showcasing a wider range of species, we’re highlighting one very unique anthiine. Odontanthias katayamai is a member of the deep bodied genus Odontanthias, which is exclusively deepwater and distributed all over the Pacific and Indian Ocean, with one member residing in the Atlantic Ocean. Of the many species of Odontanthias, only five are available to the trade.
Odontanthias is a fascinating genus of deepwater anthias that are very stout in built with large eyes and mouths. Many species are extremely ornately decorated, with elaborate threaded filaments arising from all unpaired fins and unusual tail morphologies. In O. elizabethae, the tail filaments are long and tapering, while in O. katayamai they are rounded and clubbed.
The fish in subject here today is not new to the world, and certainly not to this blog. Odontanthias katayamai has been broadcasted to death every time it appears in Japan, but this is the first time that such clear photos have ever been provided for the public. It was really opportune how this fish ended up in Osaka during our visit, and allowed for some nice photos while it posed with all the finesse in the world.
Odontanthias katayamai is so far known only from Japan and Taiwan, where it lives in very deep waters up to depths of 700ft. In cooler months where the water temperature drops, they, like many other deepwater fish, can be found shallower as they migrate nearer to the surface. In the past, this species has been extensively confused with the Indo-Pacific Odontanthias chrysostictus, but a detailed post highlighting this error has been made, and the two species can be differentiated based on tail characteristics.
As with many deep water fish, O. katayamai is actually not uncommon at depth. In Japan at least, this species is a rather common by-catch of commercial fishing entities or by sport fishermen. At 600ft, this fish is commonly hooked on the line. Unsurprisingly, these never make it due to the trauma brought about by the rapid ascent from deepwater to the surface. It’s the same old story that we’ve been preaching in every deepwater fish post. The photos above show some example of O. katayamai suffering from DCS brought upon by hook and line fishing. Swim bladder trauma leading to buoyancy issues as well as eversion of the anus are signs of improper and rapid ascent.
Despite its prevalence in the wild, these are incredibly scarce in the trade and comes with a hefty price tag. Because of their deepwater nature, rebreather diving is just about the only way to go but in Japan that is not exactly a viable option. The few that do enter the trade are mostly from fishing that do miraculously survive, either by sheer luck or by intentional care taken to reel it up slowly. How exactly does this happen, I am unsure.
In this beautiful species, the ground colour is a luscious salmon with a rose wash, which intensifies into a mangosteen purple toward the tail. The coloration of this fish has led to its Japanese name of “Rose-Handai”. Handai means perch, or specifically anthias, with rose referring to the coloration. The head is encased in a yellowish-green helmet which travels up along the dorsal fin, where it is adorned in spots of the body’s coloration. Conversely, the body is stellated with spots of the dorsal fin’s coloration. The tail is trimmed in yellow and the two lobes are slightly pronounced and edged in red. All its fins with the exception of the pectorals and caudal are festooned with trailing filaments.
In Japan, Deep Sea Challenger seems to be one of the few providers of this species. This particular one has been sitting on the shelves for years, left unsold and unwanted. The length it has stayed with them however has allowed the fish to fatten up and acclimate well to aquarium life. Normally shy, this particular one hogged the front panel posing relentlessly for photos. In comparison, another specimen living in Dr. Shimokobe’s home (which we will feature in part 3) was painfully reclusive and nearly impossible to photograph.
It was a rather opportune time for us in Osaka. Had we been there even a month earlier we wouldn’t have had the chance to see this fish. This O. katayamai resided for a long time in Okinawa, where Deep Sea Challenger is situated. It nearly made its way to Singapore, but it ended up going to an undisclosed buyer instead.
While at Osaka, Koji took me to see a young man named Yuma Yasuda. In a dark shadowy tank at the end of the room was the faint glow of the yellow helmet belonging to this fish. It was immediately recognisable that this anthias was the same one that had been shelved at Deep Sea Challengers for a long time, and how uncanny that it ended up here in Osaka.
We’ve included a HD video of this species above. It’s enthralling to say the least, watching the ribbony fin extensions trail around as the fish makes calculated turns around its aquarium. The tank is sparsely stocked, and the only fish comparable in size is a medium sized Clarion Angelfish. A small Odontanthias borbonius, Centropyge joculator and Liopropoma mowbrayi also reside in this tank.
I personally am in love with the aqua scape of this aquarium. The rocks are densely arranged to form a network of interlacing caves and tunnels, and is clearly appreciated by the fish as it makes its rounds weaving in and out like a needle in soft cotton. The catacomb honeycomb structure is always an added bonus when keeping deepwater fish. Adding ledges and overhangs are also plus points that you can utilise. While dense rock work is frowned upon in fast moving systems of the shallow reef systems that most try to replicate, it is encouraged in deepwater set ups. However balancing density with porosity is important, so as to ensure adequate water movement within the rocky maze.
The dimly lit tank is only very weakly illuminated by blue LEDs, casting shadows and obscurity in many parts of the aquarium. It’s extremely satisfying to see a deepwater tank that is well composed, well executed and cleverly thought out. To house such an elite species would obviously require nothing but the optimal, but that being said, the optimal should always be provided in everything and for everything that’s being done.
It’s not everyday you get to see an Odontanthias katayamai, and we hoped our photos and videos have captured its beauty as true to life as possible. That being said, there are five species that have entered the trade so far, and the other four in ascending order of rarity are Odontanthias borbonius, O. fuscipinnis, O. unimaculatus and O. chrysostictus. Apart from O. unimaculatus, i’ve had the fortune of seeing all the other four species in person and have taken some photos of them as well! Below is a small collage of the four.
There are many other species that have appeared, such as O. rhodopeplus, O. tapui, O. elizabethae etc. However these are never alive when caught and are never offered to the trade, so strictly speaking there are currently only five that were at some point obtainable. That’s definitely going to change in the future though, with so much deep diving going on these days in remote areas, it’s only a matter of time before a new Odontanthias is offered.
Once again, a big and sincere thank you to Koji Wada and Yuma Yasuda for this opportunity. We’ve attached a gallery below for more photos of this stunning species. Stay tuned for Part 3!
