News / Species Spotlight / Species Spotlight - Blue Hippo Tang (Paracanthurus hepatus) (11/17/16)

Species Spotlight - Blue Hippo Tang (Paracanthurus hepatus)

Species Spotlight - Blue Hippo Tang (Paracanthurus hepatus)
Long before it became famous as Dory in Finding Nemo, Paracanthurus hepatus was a star among aquarists, as it is without a doubt one of the most singularly beautiful and iconic species of coral reef fish. This one-of-a-kind species boasts a deep and vibrant shade of blue throughout its body, accented with a bright yellow tail and a peculiar black pattern that, depending on your point of view, either resembles an artists palette or a 6.

This species also boasts the dubious distinction of seemingly having more common names than just about any other coral reef fish. Here at Quality Marine we refer to it as the Blue Hippo Tang, but youll also see it mentioned as the Palette Surgeonfish, the Pacific Blue Tang, the Hepatus Tang, the Regal Blue Surgeonfish, the Wedgetail Blue Tang, and as the Letter 6. This last name is used by the Indonesian divers that collect this species for the aquarium trade.

While it may be a common fish in aquarium stores, P. hepatus is actually a fairly uncommon species in the wild. It prefers habitats with clear waters and heavy currents, often along the outer edges of a coral reef, which are abundant in the gelatinous zooplankton that makes up the bulk of its diet. For this reason, you generally wont find this fish in a stagnant lagoon or a tide pool, as there is little for it to eat there. Of course, this is quite different from most other species of tang and surgeonfish, which make a living feeding upon algae and detritus, though another species occasionally seen in the aquarium trade, Acanthurus thompsoni, also feeds in this manner and has a remarkably similar shape to Paracanthurus.

The Blue Hippo Tang is found across most of the Indo-Pacific, from the East African shoreline to Japan, Australia and most of the Central Pacific; however, there are some places where it is noticeably absent. For instance, you dont see this fish in the Red Sea or in French Polynesia or in Hawaii, though its not clear why, as there surely must be plenty of food for it there. Interestingly, specimens from the Indian and Pacific Oceans are somewhat different in appearance, with those from the Indian Ocean typically having a pale or yellow belly, while those from the Pacific tend to be solidly blue. Its possible these will eventually be treated as separate species or subspecies, as this recently happened to the Indian and Pacific Ocean Regal Angelfishes.

In captivity, P. hepatus is an easy and hearty species to care for, though many aquarists often struggle with it. Like most other surgeonfishes, this species is prone to Cryptocaryon (=saltwater ich) infection which, if left untreated, will often kill this fish quite quickly. To avoid this issue, it is wise to buy from a reliable source and to always quarantine in a separate aquarium. Another common malady is fin erosion and color loss, which is usually the result of poor water conditions. Once settled into an aquarium, this is an active and remarkably peaceful fish and one which can be mixed with almost any other species, including other surgeonfishes. In larger aquariums, its also possible to keep multiple Blue Hippo Tangs together, though there will often be some fighting between them as they work out a dominance hierarchy. If possible, purchase smaller specimens and add them together, as this will usually reduce problems with aggression.

With a maximum size of around eight inches, this energetic species will need a suitably large fish tank, with a recommended size being six feet or more in lengthfor this reason, the Blue Hippo Tang is a poor choice for a beginner aquarist with a small aquarium. Feed a mix of dry herbivore foods and sheets of dried algae. As a zooplanktivore, it might be tempting to feed a diet heavy in frozen shrimp, but this is likely to be far more protein-rich than what is fed upon in the wild and could potentially lead to issues with obesity and fatty liver disease. It is not uncommon to find overfed specimens that are practically round in dimensions, but this is unquestionably poor for their long-term health.

For the most part, P. hepatus is entirely safe to mix with corals and other invertebrates; however, the occasional rogue specimen has been known to nibble the mucous of larger, fleshy corals (scolys, lobos, etc).

Finally, it bears mention that Dory is actually mildly venomous, though they dont mention that in the movies! The venom glands are associated with the dorsal fin spines and provide an excellent defense, as this fish will quickly wedge itself into rocks and corals when threatened, pointing its noxious spines outward. For this reason, always be mindful of where you put your fingers when moving rocks around, as you never know where your Blue Hippo Tang might be hiding. If stung, the venom is not much worse than a bees sting and can be neutralized by running the wound under hot water.

One of the most exciting developments regarding this fish was the recent announcement that it has at long last been successfully bred in captivity by researchers at Rising Tide Conservation and the University of Florida. As this species has long been one of the most popular and heavily collected fishes, this is an exciting and important breakthrough with the potential to help lessen pressure on wild stocks and move the aquarium industry forward in the right direction. Quality Marine is proud to support these initiatives and to be able to offer these remarkable captive bred specimens.