The Exciting Conclusion

       You may recall when you last looked at the blog, we were exchanging emails with our local experts

Black Surgeon Ctenochaetus hawaiiensis Transitional Phase

regarding the mystery fish seen at City of Refuge.  After a bit of research and discussion, it was clear that this was a surgeon fish of the genus Ctenochaetus.  Jack Randall was hoping for a state record, a waif from the south Pacific, C. binotatus.  I thought that this was a pretty good picture, but the scientific community would demand better.  I didn't think that Sandra and I would stand much of a chance finding one fish in the bay and I don't go deeper than fifteen feet, so this was set aside.

    At this point, our friend John Hoover, contacted me with an idea.  Along the lines of my initial inquiry,  he thought it likely that this represented a Black Surgeonfish in the late stages of changing from a juvenile to mature (all black) adult.  I'm showing you here a photo of that immature.  It is one of those Keikis so different and remarkable that it gets

Chevron Tang For Sale!

a separate common name...the Chevron Tang.   Sadly, you have a better chance of seeing that fish in an aquarium than I have of seeing it in the ocean.  This immature is for sale on the internet from $60 plus shipping.  The species name, hawaiensis, suggests an endemic, but the fish is found through much of the Pacific.   Luckily, at least here on the Big Island, we have a fair number of Black Surgeonfish.  So while the aquarium trade is scooping them from somewhere, they have yet to put a serious dent in our Black Surgeon population.

     That being so, you may wonder why I haven't seen an immature.  The answer, as John Hoover pointed out in his email, can be found on page 303 of his book, The Ultimate Guide to Hawaii Reef Fishes....  The immatures are found between 60 and 100 feet in dense coral cover.  Hence, we snorkelers stand little chance of seeing one of these gorgeous little fish.  And isn't it interesting (and  more than a little

Black Surgeon with Friends at the Dog Beach

depressing) that divers stealing fish off the reef for the aquarium trade have such a better chance of seeing this lovely fish than we do?

     A word about the fish we pictured.  On his pathway to a mature coal black phase, he has the yellow tail and blue periorbital markings found in another member of the same genus.  Does ontogeny recapitulate phylogeny, or what?  I have little doubt that our identification is correct, yet we are only speculating.  This picture, to the best of my knowledge, is the only one of the Black Surgeonfish in this transitional phase!  At least it is the only one like it on Google images.  (And what Mr. Google doesn't know, ain't worth worryin' about .)

      It is interesting that aquarists have ways of keeping these immatures small and in the immature coloring far longer than would be the case in the wild.  As John Hoover speculated, the fish we saw was rapidly changing to the adult coloration.  Just a couple days later, it may be completely black.
So black and active is the adult that I don't have a good picture.  If you go swimming off Paul Allen's Reef I'm sure you will see a Black Surgeon.  But you probably won't see the immature.

jeff