Oxymonacanthus halli: LiveAquaria’s offers the Red Sea harlequin filefish

LiveAquaria's first Diver's Den release of the uber-rare, uber-expert-only, Red Sea Longnose Filefish, Oxymonacanthus halli. Image copyright, and courtesy of, LiveAquaria.com

LiveAquaria produced and delivered, a fully conditioned specimen of the Red Sea “Harlequin” Filefish, Oxymonacanthus halli. I cook dinner for my wife and son, go run some errands, and come home to a Facebook posting from Dr. Matt Wittenrich, waving this picture of Oxymonacanthus halli from LiveAquaria on my wall, there, taunting me publicly. It’d be like, oh, what the Peppermint Angelfish is for the rest of you. Talk about a virtual smack in the face, the kind that leaves your jaw on the ground while grinning ear-to-ear. Did I mention it was already SOLD by the time I found out about it?! Someone just got really lucky.

This Red Sea version of the Longnose, aka. Orange Spot, aka. Harlequin Filefish, Oxymonacanthus longirostris, has been on my dream list ever since I succeeded in breeding and rearing O. longirostris. But honestly, I had written this fish off as one of those Fisheous unobtaniatumi (or something like that) – Kevin Kohen’s name for the whack hole-in-the-wall type marine fish species that the everyday aquarist isn’t even aware they exist (eg. Synchiropus circularis).

Oxymonacanthus longirostris - the more common sister species to O. halli

In every sense of the word, I had written O. halli off as a fish I’d dream about, but would never see. Not many people have ever kept this species in captivity, but we can presume that it is a SPS feeder much like the sister species O. longirostris. Thus, probably everything written on the subject of care for the Harlequin Filefish is probably applicable to the Red Sea Harlequin Filefish. Steve Krogh, Operations Manager at the Rhinelander facility (Diver’s Den & the Coral Farm) confirms that Oxymonacanthus halli appears to behave the same, and require the same husbandry as O. longirostris.

They allow only passive fish for tankmates, and by the time the fish are ready for sale, they are trained to eat enriched Brine Shrimp and Mysis, as well as Nutramar Ova. Based on that information, this is definitely a species I would recommend only for people who will either let it graze their SPS tank, or otherwise give it very specific customized care that Oxymonacanthus filefish require. And even then, I might go so far as to say that really, only those who’ve kept the regular Harlequin Filefish successfully, should be jumping on the bandwagon to snap up this exceptionally rare-in-the-trade species.

Matt Pedersen

Matt Pedersen is an interactive software developer and part-time fly fishing guide originally from Chicago, IL and current living in Duluth, MN, USA. Additionally, Matt has experience as a professional orchid breeder and certified fly rod builder. Matt has been a marine aquarist for 23 years, and an aquarist for 28+. After spending time on every side of the aquarium industry (retail, commercial and private maintenance & installation, wholesale, hatchery), he currently considers himself a "professional hobbyist". Most recently, Matt has currently spawned 22 species of marine fish, successfully raising 8 of them to date including one worldwide first (the Harlequin Filefish, Oxymonacanthus longirostris), as well as attempted another 6 invertebrate species to date. Most all of this was accomplished with less than 100 gallons of total working capacity, and all in closed culture. In 2010, Matt Pedersen was selected as the breeder of choice to work with the now famous "PNG Lightning Maroon Clownfish" from the SEASMART program, and chronicles the efforts to propagate this one-of-a-kind fish online at The Lightning Project. Matt Pedersen is credited with starting MOFIB (Marine Ornamental Fish & Invertebrate Breeder's Association) and writing for multiple publications including Coral, Koralle, Practical Fish Keeping, Reef Hobbyist Magazine and Reef Builders. Matt has spoken at numerous aquarium clubs and events from coast to coast. He currently sits on the MBI (Marine Breeding Initiative) Council, a project dedicated to bringing the concept of a unified Marine Breeder's Award Program to hobbyist organizations across the country and around the globe. In 2009, Matt was awarded "Aquarist of the Year" honors by both IMAC West and MASNA in recognition of his accomplishments and contributions to the marine aquarium hobby. Last updated October, 2010.