Part of the excitement about being a fancier of marine life is the ability to follow leads of curiosity, no matter how improbable the odds of success in finding something meaningful, even when you don’t really know what you are looking for. Recently we stumbled upon one grainy picture of an exceptional clown tang from the Seychelles which led us on a photo hunt that yielded more than a handful of interesting fish.
It’s hard to explain how one picture with location data can appear so promising and stimulate our sleuthing instincts, but more often than not our ‘spidey sense’ can turn us on to something interesting. The image above was that first clue to a puzzle that we haven’t yet pieced together, but we believe there’s something in the population of Acanthurus lineatus from the Seychelles warranting further investigation.
A ‘normal’ clown tang should have fairly straight body stripes which curve gently around the flanks and the even blue lines are bordered by an even black trim. Above you can see a typical clown tang with the cooky-cutter pattern which is widespread from the Western Indian Ocean to the central Pacific Ocean. Maybe it’s because we really love this particular species, and have examined hundreds of specimens over the years, but the stripes of the specimen pictured below show just the slightest deviation from the normal pattern.
In the good and clear side-profile pictures of some specimens of clown tangs in the Seychelles, the squigglyness of the side stripes becomes more apparent. Again on its own this abnormality is hardly anything to mention, let alone write about, but further meta-searching led us to find even more oddball A. lineatus with ever more extreme aberrations.
Once again, if we saw one of these clown tangs at the local fish store or in the wild, a single specimen with abnormal stripes and patterns is not enough to raise any flags. Aberrations of color and pattern happen in practically all reef fish that we know about and it’s relative what is considered ‘normal’ for a species. However in the Seychelles the aberrations seemed to be piling up and more common than regularly striped clown tangs.
It’s a curious thing to be investigating a hunch about marine fish through piles of online photographs, and even curiouser to actually stumble across what you seek, even when you don’t know what it is you were looking for. So you can imagine how stunned we were when we actually uncovered an extreme example of the aberrant clown tangs which is a ‘smoking gun’ for something that we can’t explain.
There are plenty of clown tangs in the Seychelles which show relatively normal color and pattern but there are enough unusual ones for us to postulate that some phenomenon is affecting their appearance. With very little data to go on, our first and only hypothesis about these unusually patterned clown tangs is that there may be some degree of localized inbreeding in this region, similar to the Koi Queen Angelfish of St. Paul’s Rock.
In this island off of Brazil the Holacanthus ciliaris specimens express very unusual colors and patterns, and even odd finnage due to well-documented inbreeding in this isolated rock in the Atlantic ocean. The Seychelles are moderately isolated from other west indian ocean islands but it still constitutes a large enough area that the resident population is relatively large. Genetic analysis alone can confirm or refute that genetics are even involved in the odd appearance of these clown tangs but if you ever end up diving or snorkeling in the Syechelles, do be on the lookout for some oddball Acanthurus lineatus.