The Fish With the Fishy Name

“Mark, do we have any assfish?” 

It was not the question I expected when the Academy’s president, Scott Cooper, called upon my department, Ichthyology, for help.  

Assfish? There are 36,128 species of fishes. We know that because back in the 1980s, an ichthyologist named Bill Eschmeyer started a Catalog of Fishes at The California Academy of Sciences. But as far as I knew, none of those species were commonly known as assfish. 

Academy staff were preparing to open the new exhibition Extreme Deep: Mission to the Abyss, but I didn’t put two and two together.

Head of the bony-eared assfish, a deep-sea species of cusk-eel found in tropical and subtropical oceans. Photo by Mark Sabaj/ANS

 I knew of wild ass, Equus africanus, because I had grown up near Chicago where The Field Museum had one mounted in a glass display case. I knew of pinworms, aka Enterobius vermicularis, because a colleague of mine (who used a less refined word) had them as a kid and once told me a funny story about how his mom plucked them out at night with tweezers and a cold flashlight. But assfish was news to me. 

A quick Google search confirmed my worst fears. There is such a thing as an assfish. Not only that, but it apparently has bony ears. How could ichthyology — by far the noblest of all the -ologies — have assigned such a puerile and vulgar name to one of its own? 

The bony-eared assfish is a deep-sea species of cusk-eel found in tropical and subtropical oceans down to 4,415 meters (14,485 ft). It is the only known member of its genus, Acanthonus, which renders unnecessary the “bony ear” part of its common name. Only if there were multiple species of assfish would one need a common way to distinguish them, such as big-eared assfish, rabbit-eared assfish, Spock-eared assfish, etc.  

Furthermore, fish do not have ears, at least not in the common sense of the word. The sense of hearing in most fishes depends in part on small bones called otoliths buried deep within the head. And otoliths are always bony. So bony-eared is rather redundant for a fish. 

The name Acanthonus armatus was proposed by the German ichthyologist Albert Günther for a peculiar specimen trawled up off New Guinea by the HMS Challenger, a naval ship chosen to undertake the first global marine research expedition in 1872. When naming a new species, taxonomists often highlight its most conspicuous features and offer an etymology to describe such inspirations. But like other taxonomists of his time, Günther provide no such explanation. 

Fortunately, the ETYFish Project led by fish historian Christopher Scharpf has researched the origins of over 42,200 scientific names applied to fishes. As he points out, the name Acanthonus stems from the Greek words akanthos (spine) and onos (cod-like fish), whereas armatus is Latin for “armed.” So the scientific name translates to “cod-like fish armed with spines.” Günther’s description begins “head large and thick, armed in front and on the opercles with strong spines…” but mentions neither bony ears nor asses. 

So, how do we get to bony-eared assfish? As Scharpf points out, the early Greeks also used the word onos to mean ass or donkey. One guess is that someone familiar with classical Greek (and perhaps internet search engines) decided that translating onos to assfish would generate far more interest in this obscure species than cod-like fish. That same person presumably thought the strong spines on the species’ opercles resembled bony ears. Personally, I would have chosen spiny cod-like fish, as this remains truer to Günther’s scientific name. But I am neither fishmonger nor web marketer.

You can see an assfish specimen in the exhibit Extreme Deep: Mission to the Abyss. Photo by Mark Sabaj/ANS

Anyway, upon checking the Academy’s fish collection, I was disappointed to see that we had no specimens of Acanthonus armatus. Checking an online database, I saw that the largest collection of the aforementioned assfish is at the University of Florida. So I called upon my curatorial colleague Rob Robins, and he graciously gifted two beautiful specimens to the Academy. 

Visitors to Extreme Deep: Mission to the Abyss, which runs April 2 through July 24, can see these specimens in a special section devoted to deep-sea specimens pulled from the Academy’s collection.  

As an aside, one wonders if the same person who immortalized the common name bony-eared assfish will now turn to other scientific fish names that incorporate the word onus. Will Typhlonus nasus become the nosy blind assfish or Holcomycteronus brucei become “Bruce’s furrow-nosed assfish? Only time (and clicks) will tell. 

By Mark Sabaj, PhD, Academy Collection Manager of Fishes 


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