News / Species Spotlight / Species Spotlight -Fantastic Tangs and Where To Find Them (09/22/17)

Species Spotlight -Fantastic Tangs and Where To Find Them

Species Spotlight -Fantastic Tangs and Where To Find Them
Among aquarists, Zebrasoma is arguably the most popular genus in the surgeonfish family, and for good reason. These species are (almost) all beautifully colored, attractively patterned and often relatively small in size, perfect for displaying in a modestly sized home aquarium. There are sunny yellows, regal purples and inky blacks. There are polka dots and pinstripes and sailfins. These stately fishes are what all other acanthurids must aspire towards, so lets take a moment to explore who they are and where they occur.
The Sailfin Tangs
Z. veliferum and Z. desjardinii are a pair of sister species divided into the Pacific and Indian Oceans, respectively. Both sport exaggerated dorsal and anal fins, which fit proportionally with the relatively large size of these fishes. The Sailfin Tangs are giants among Zebrasoma, tipping the scales at well over a foot in length (compared to others in the genus which are more modestly proportioned, typically no larger than around 8 inches). The two are easily told apart thanks to the more elaborate patterning on Z. desjardinii, which has numerous orange spots along its belly and a more prominently spotted face. Its also typically shows less of the underlying striped colors that are seen in its Pacific sibling, making for a somewhat darker appearance. Though both are quite beautiful species, the edge here has to go to Desjardins Sailfin Tang. And, for those wondering about the enigmatic nomenclature, this beast is named for 19th-century French zoologist Julien Desjardins, an early collector of marinelife in the waters of Mauritius.

The Purple and Gem Tangs
The Western Indian Ocean is home to a pair of closely related species whose beauty and rarity make them among the most desirable in this genus. The Purple Tang (Z. xanthurum) is a well-known species from the Red Sea (and nearby waters around the Arabian Peninsula) which is always in demand among aquarists. Its deep purple coloration is accented by a bright yellow tail (alluded to in the scientific name), while a series of dark lines and spots add an extra dash of opulence. Its these markings which hint at the close relationship this species shares with one of the true jewels of the ocean, the Gem Tang (Z. gemmatum). This polka dotted piscine occurs in a number of locations to the south, including Madagascar (where most aquarium specimens originate), Mauritius, South Africa and other nearby islands. It too has a yellow tail, but the body is quite black. Since there has historically been relatively little collection for the aquarium trade within its range, the Gem Tang has long been one of the most expensive species of reef fish, putting this beautiful creature out of reach for most (though perhaps captive breeding can help address this in the future).

The Black Tang
On the other side of the Indo-Pacific, we find the Black Tang (Z. rostratum), a species whose beauty comes from its subtlety and simplicity. As a juvenile, it lives up to its common name, being an inky black shade throughout; however, as it matures, a griseous splash of color infiltrates its back in a manner most macabre. The look is both ghastly and gorgeous, and certainly unique among fish kind. Equally of note is the greatly exaggerated length of the mouthparts in this species (referenced in the scientific name rostratum), making this the Cyrano de Bergerac of tangs. Youll find this fish throughout Polynesia, from the Cook Islands to Pitcairn and north into the Line Islands. Rarely, specimens have even been found in Hawaii, though these are considered to be waifs. Since so little collection occurs in these far off lands, this is another tang with a sizable price tag, and thus a feather in the cap of all those fortunate enough to have one swimming about in their aquarium.

The Yellow and Scopas Tang
If there is an ugly duckling in the Zebrasoma family, it is surely the earthen clad Z. scopas, whose somber hue inspires devotion in relatively few aquarists. If the Scopas Tang has anything going for it, it would perhaps be its ubiquity. This is unquestionably the most widespread member of the genus, occurring almost everywhere in the Indo-Pacific, save for the easternmost portions. There is, however, one noticeable absence. There are no Scopas Tangs in Hawaii. Instead, we find replacing it one of the most illustrious of reef fishes, Z. flavescens, the Yellow Tang. Like an aquatic ray of sunshine, the Yellow Tang brightens all who bask in its glory. Vast schools abound in Hawaiis waters, gracefully plucking at whatever algal morsels they come across in their daily foraging.

But there are yellow tangs found further afield than the Aloha State. For instance, the dominant species in the Ogasawara Islands south of Japan, as well as the nearby Mariana Islands, is Z. flavescens. This illustrates the interesting faunal connectivity that these two distant regions, Hawaii and Japan, share. The occasional Z. flavescens can also be found in other portions of Japan, and, in exceptional cases, even into the northernmost islands of the Philippines.

There are additional reports of yellow tangs elsewhere in the Pacific, but this is where the plot thickens. In the Philippines, where these xanthic Zebrasoma are often collected for the aquarium trade, there is ample evidence to suggest that these are not the true Z. flavescens but, rather, are simply unusually yellowed variations of the widespread Z. scopas. Whether through hybridization or some random mutational quirk, the Scopas Tang can turn itself into a faux-Yellow Tang of sorts, though it can still be identified thanks to the faint trace of striations which shows through (a feature which the true Yellow Tang never possesses). Similar specimens have also been observed in portions of Micronesia.

These shouldnt be confused with the outrageously aberrant koi tangs which occasionally appear in Z. scopas. Most of these are said to originate from around Java, and it is quite possible that this peculiar mutation is caused from a hybridization between the Indian and Pacific Ocean populations in this region of geographic overlap.