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Paracanthurus hepatus
This weeks fish of the week is the instantly recognisable star of Disney’s 2016 film ‘Finding Dory’. The Blue Tang goes by many common names, including the hippo tang and regal tang (or even a mix of all of the above)! It is a member of the surgeonfish family Acanthuridae, but sits alone in the genus Paracanthurus as the only species. Surgeonfish have a distinctive set of razor-sharp scal-pels near their caudal (tail) fin. These modified scales are used for defence and as weapons during conflict. Most surgeonfish have one set of caudal spines, but some weald multiple pairs. Many injuries have been inflicted on fish-keepers by mishandling a surgeonfish!
The Blue Tang’s scientific name provides somewhat of a misnomer. The genus name, Paracan-thurus, translates from Greek to “near acanthurus”, relating to the close relation to the main family of surgeonfish Acanthurus. Acanthurus derives itself from Greek. “Akantha” meaning spine, and “ura” translating to tail. It is the second half of the species name which provides the oddity. Hepa-tus translates from the Greek word for liver (liver cells in the body are called hepatocytes). Why would a predominantly blue fish be likened to a liver? The scientist who named this species was none other than Carl Linnaeus, the father of scientific nomenclature. It is believed when he first described this species in 1766, he was provided with a preserved specimen. The deceased ani-mal had lost much of its vivid blue colouration and had turned an irony red, similar to the colour of the liver. Scientific naming rules state the name must not be changed from the original scientific description. Sometimes names change but this is usually when it has been previously described by someone else originally, and they both describe the same species. In this instance the earliest discovery will become the official name. Scientific names can also change if research shows a species doesn’t belong to a previously thought family. This could lead to a change of genus name but not species. One wonders whether Linnaeus ever found out the species was actually blue be-fore his death twelve years later in 1778.
The Blue Tang should not be an impulse purchase species, for a couple of important reasons. They can grow in excess of 30cm and require a large aquarium for long term care. They are a fast and agile fish, requiring lots of swimming space especially once large. They are also prone to dis-ease in poor water quality. They, like many other species of surgeonfish, are prone to marine whitespot. External parasites can be difficult to treat in a reef aquarium due to invertebrates sensi-tivity to chemicals used in the medications. It is recommended to have a hospital/quarantine tank for delicate species such as tangs before adding to a mixed reef aquarium to help prevent out-breaks of disease.
Tagged in: Fish of the Week Archive - Marine