Belongs within: Acanthuriformes.
Contains: Acanthurus.
Reef surgeons
Published 22 July 2026
For better or worse, the chains of pop culture bind us all. And so, for the last couple of decades, if anyone is asked to picture a tropical fish, one of the first two examples to come to mind is going to be this:
Commonly known as the regal tang or blue tang, Paracanthurus hepatus has become immediately recognisable as the ‘Dory’ of Finding Nemo. In real life, it is one of over eighty species of tropical marine fish making up the family Acanthuridae, the tangs or surgeonfishes (dories, of course, are a quite different family of fishes). The name ‘surgeonfish’ refers to the presence of sharp spines, representing modified scales, on either side of the caudal peduncle that function in defence. In members of the genera Naso and Prionurus, these spines are fixed in place and multiple pairs of spines may be present. In other genera, the caudal spines have developed into a single pair of erectile blades, folded against the peduncle when not in use. Other characteristic features of the family include a small mouth with a single row of teeth and nonprotrusible premaxilla, and large dorsal and anal fins extending much of the body length. Like many other tropical reef fishes, acanthurids are often brightly coloured. In the unicornfishes of the genus Naso, a distinct horn-like process may be present on the forehead. Some acanthurids may reach significant sizes; the whitemargin unicornfish N. annulatus may grow up to a metre in length.
Acanthurids are most commonly found around reefs where the majority of species feed on a diet of algae. However, other food sources such as small invertebrates may also be taken. Jones (1968) identified four basic classes of feeders among acanthurids of the Hawaiian archipelago: zooplankton feeders that primarily took small crustaceans, grazers that picked up mouthfuls of sand containing micro-algae and detritus, and two classes of browsers biting off pieces of macro-algae. One class of browser focused on leafy and large fleshy seaweeds; the others fed on smaller filamentous algae. Spawning often occurs at reef edges. The postlarval stage of acanthurids, known as the acronurus, is laterally compressed, transparent and pelagic, feeding on plankton in open waters. Acronurus larvae may reach one or two years in age, and sizes of ten to fifteen centimetres, before finally settling down on a suitable reef.
Modern acanthurids are divided between five genera (following Sorenson et al.’s [2013] synonymy of Ctenochaetus with Acanthurus) but a further eighteen genera have been named from the fossil record going back to the Eocene (Tyler & Micklich 2011). The majority of these taxa come from the Monte Bolca deposit of Middle Eocene Italy, one of world’s foremost localities for early Cenozoic marine fishes. These fossils indicate that the divide between the subfamilies Nasinae (including the modern Naso) and Acanthurinae (including all other modern genera) occurred early in the family’s history, and that the acanthurids have been prominent members of the tropical reef fauna ever since.
Systematics of Acanthuridae
Acanthuridae [Acronuridae, Caprovesposidae, Naseidae, Teuthidae]
| i. s.: Eonaso deaniFJ05
| CaprovesposusP93
| Acanthonemus subaureus (de Blainville 1818) [incl. A. filamentosus Agassiz 1833–1844]B80
| Tylerichthys Blot 1980B80
| `--*T. nuchalis (Agassiz 1833–1844) [=Naseus (Naso) nuchalis]B80
| Eozanclus Blot & Voruz 1970B80
| `--E. brevirostris (Agassiz 1833–1844) [=Zanclus brevirostris]B80
|--NasinaeS66
| |--Callicanthus Swainson 1839S66
| | `--C. lituratus (Bloch-Schneider 1801) (see below for synonymy)S66
| |--Axinurus Cuvier 1829S66
| | |--*A. thynnoides Cuvier & Valenciennes 1835 [=Naseus thynnoides, Naso thynnoides]S66
| | `--A. minor Smith 1966S66
| `--Naso Lacepede 1802 (see below for synonymy)S66
| | i. s.: N. caesius Randall & Bell 1992MM09
| | ‘Naseus’ leptopeltis Bleeker 1875 (n. d.)S66
| | N. maculatus Randall & Struhsaker 1981MM14
| | ‘Monoceros’ marginatusJR10
| | N. minorWM93
| | ‘Monoceros’ olivaceusJR10
| | N. rectifrons (Agassiz 1833–1844) [=Naseus (Naso) rectifrons]B80
| | ‘Naseus’ tripeltis Cuvier & Valenciennes 1835 (n. d.)S66
| | ‘Naseus’ unicolor Lienard 1839 (n. d.) [incl. Axinurus dipeltis Val in Guichenot 1863]S66
| |--N. (Naso)S66
| | |--N. (N.) unicornis (Forskål 1775)S66 (see below for synonymy)
| | |--N. (N.) annulatus (Quoy & Gaimard 1825)S66 (see below for synonymy)
| | |--N. (N.) brachycentron (Cuvier & Valenciennes 1835) (see below for synonymy)S66
| | |--N. (N.) brevirostris (Cuvier & Valenciennes 1835) (see below for synonymy)S66
| | `--N. (N.) herrei Smith 1966S66
| |--N. (Atulonotus Smith 1955)S66
| | |--N. (*A.) hexacanthus (Bleeker 1855) (see below for synonymy)S66
| | |--N. (A.) lopezi Herre 1927S66
| | |--N. (A.) tapeinosoma (Bleeker 1854) [=Priodon tapeinosoma, Naseus tapeinosoma]S66
| | |--N. (A.) thorpei Smith 1966S66
| | `--N. (A.) vomer (Klunzinger 1871) [=Naseus vomer]S66
| |--N. (Cyphomycter Fowler & Bean 1929)S66
| | |--N. (*C.) tuberosus Lacépède 1802S66 (see below for synonymy)
| | `--N. (C.) vlamingii (Cuvier & Valenciennes 1835) (see below for synonymy)S66
| `--N. (Rhinodactylus Smith 1956)S66
| `--N. (R.) fageni Morrow 1954 (see below for synonymy)S66
`--AcanthurinaeTB99
|--Proacanthurus teniusND13
`--+--Prionurini [Prionurinae]TB99
| |--Prionurus Lacepede 1804 [=Acanthocaulis Waite 1900]S66
| | `--*P. microlepidotus Lacepede 1804 [=*Acanthocaulis microlepidotus, P. microlepis (l. c.)]S66
| `--Xesurus Jordan & Evermann 1896S66
| |--*X. punctatus (Gill 1863) [=Prionurus punctatus]S66
| |--X. biafraensis Blache & Rossignol 1961S66
| |--X. laticlavius (Valenciennes 1846) (see below for synonymy)S66
| |--X. maculatus (Ogilby 1887) [=Prionurus maculatus, Burobulla maculata]S66
| `--X. scalprum (Cuvier & Valenciennes 1835) (see below for synonymy)S66
`--+--Zebrasoma [Zebrasomini]TB99
| |--Z. veliferum (Bloch 1797)B-RW17, MM09 (see below for synonymy)
| `--+--ParacanthurusB-RW17
| | |--P. hepatus (Bleeker 1859)TB99, M58 [=Acanthurus hepatusM58, Teuthis hepatusJR10]
| | `--P. theuthis (Lacépède 1802) [=Acanthurus theuthis]M58
| `--+--Z. flavescens (Bennett 1828)B-RW17, M58 (see below for synonymy)
| `--+--Z. rostratum (Günther 1875)B-RW17, MM14
| `--Z. scopas (Cuvier 1829)B-RW17, MM09 [=Acanthurus scopasM58]
`--AcanthurusTB99
Nomen nudum: Naseus intermedius de Zigno in Blot 1980B80
Callicanthus lituratus (Bloch-Schneider 1801) [=Acanthurus lituratus, Aspisurus lituratus, Harpurus lituratus, Monoceros lituratus, Naseus litturatus, Naseus lituratus, Naso lituratus; incl. Balistes acanthuroides Curtiss 1938, Keris anginosus Cuvier & Valenciennes 1835, Naseus anginosus, Priodon anginosus, Aspisurus carolinarum Quoy & Gaimard 1824, Naseus carolinarum, As. elegans Ruppell 1828, *Callicanthus elegans, Prionurus eoume Lesson 1831, Cyphomycter eoume, Naso eoume, Monoceros garretti Seale 1901, Acanthurus garretti, Callicanthus garretti, Teuthis nepotei Curtiss 1938]S66
Naso Lacepede 1802 [incl. Keris C & V 1835, Monoceros Bloch-Schneider 1801 non Meusch 1787, Nasonus Rafinesque 1815, Naseus Commerson in Lacepede 1802, Priodon Quoy & Gaimard 1825, Priodontichthys Bonaparte 1831, Prionolepis Smith 1931]S66
Naso (*Atulonotus) hexacanthus (Bleeker 1855) [=Priodon hexacanthus, Callicanthus hexacanthus, Naseus hexacanthus; incl. Naso genimarginatus Herre 1927, Callicanthus metoposophron Jenkins 1902, Acanthurus metoposophron]S66
Naso (*Cyphomycter) tuberosus Lacépède 1802S66 [=Acanthurus tuberosusS66, Monoceros tuberosusS66, Naseus tuberS66, Naseus tuberosusS66; incl. Naseus johnstonei Ramsay 1876S66, Acanthurus nasus Shaw 1803S66, Naseus punctulatus Cuvier & Valenciennes 1835S66, Naseus tonganus Cuvier & Valenciennes 1835S66, Naso tonganusMM14]
Naso (Cyphomycter) vlamingii (Cuvier & Valenciennes 1835) [=Naseus vlamingii, Acanthurus vlamingii, Monoceros vlamingii]S66
Naso (Naso) annulatus (Quoy & Gaimard 1825)S66 [=Priodon annulatusS66, Monoceros annulatusJR10, Priodon annularisS66, *Priodontichthys annulatusS66, Prionodon annularisS66, Teuthis annularisS66; incl. Acanthurus incipiens Jenkins 1902S66, Naseus marginatus Cuvier & Valenciennes 1835S66, A. marginatusS66, Naso marginatusS66]
Naso (Naso) brachycentron (Cuvier & Valenciennes 1835) [=Naseus brachycentron; incl. *Prionolepis hewitti Smith 1931, Naso rigoletto Smith 1951]S66
Naso (Naso) brevirostris (Cuvier & Valenciennes 1835) [=Naseus brevirostris, Acanthurus brevirostris, Priodon brevirostris; incl. Keris amboinensis Bleeker 1853, Naseus amboinensis, Priodon amboinensis, Naso coryphaenoides Smith 1955, Naseus hoedtii Bleeker 1853]S66
Naso (Naso) unicornis (Forskål 1775)S66 [=Chaetodon unicornisM58, Acanthurus unicornisS66, Aspisurus unicornisS66, Chetodon unicornisS66, Monoceros unicornisS66, Naseus unicornisM58, *Nasonus unicornisS66, Nasus unicornisS66; incl. Acronurus aegypticus Gronow in Gray 1854S66, Monoceros biaculeatus Bloch-Schneider 1801S66, Acronurus corniger Gronow in Gray 1854S66, *Naso fronticornis Lacepede 1802S66, Naseus fronticornisM58, Naseus longicornis Cuvier in Guerin 1830S66, Harpurus monoceros Forster in Lichtenstein 1884S66, Naseus olivaceus Cuvier & Valenciennes 1835S66, Naseus punikar Thiollière 1857M58, Prionurus punikar Montrouzier in Thiollière 1857 (n. n.)M58, Monoceros raii Bloch-Schneider 1801S66]
Naso (Rhinodactylus) fageni Morrow 1954 [=Cyphomycter fageni; incl. C. cavallo Smith 1955, *Rhinodactylus baixopindae Smith 1956]S66
Xesurus laticlavius (Valenciennes 1846) [=Naseus laticlavius, Prionurus laticlavius, Triacanthurodes laticlavius; incl. Xesurus clarionis Gilber & Starks 1897, X. hopkinsi Gilbert & Starks 1903, X. (Dasyacanthus) hopkinsi]S66
Xesurus scalprum (Cuvier & Valenciennes 1835) [=Prionurus scalprum, Naseus scalprum; incl. Etroplus fumosus Brevoort 1856]S66
Zebrasoma flavescens (Bennett 1828)B-RW17, M58 [=Acanthurus flavescensM58; incl. A. humeralis Bleeker 1859M58, A. rhombeus Peters 1876M58, Harpurus rhombeusM58, Zebrasoma rhombeumM58]
Zebrasoma veliferum (Bloch 1797)B-RW17, MM09 [=Acanthurus veliferM58; incl. A. hypselopterus Günther 1875M58, A. maristarum Thiollière 1857M58, A. ruppelli Bleeker 1859M58, Naseus strigatus de Vis 1884S66, A. viaged Montrouzier in Thiollière 1857 (n. n.)M58]
*Type species of generic name indicated
References
[B-RW17] Betancur-R, R., E. O. Wiley, G. Arratia, A. Acero, N. Bailly, M. Miya, G. Lecointre & G. Ortí. 2017. Phylogenetic classification of bony fishes. BMC Evolutionary Biology 17: 162.
[B80] Blot, J. 1980. La faune ichthyologique des gisements du Monte Bolca (Province de Vérone, Italie). Catalogue systématique présentant l’état actuel des recherches concernant cette faune. Bulletin du Museum National d’Histoire Naturelle C 2: 339–396.
[FJ05] Friedman, M., & G. D. Johnson. 2005. A new species of Mene (Perciformes: Menidae) from the Paleocene of South America, with notes on paleoenvironment and a brief review of menid fishes. Journal of Vertebrate Paleontology 25 (4): 770–783.
[JR10] Jordan, D. S., & R. E. Richardson. 1910. Check-list of the species of fishes known from the Philippine archipelago. Bureau of Printing: Manila.
[MM09] Moore, G., & S. Morrison. 2009. Fishes of three North West Shelf atolls of Western Australia: Mermaid (Rowley Shoals), Scott and Seringapatam Reefs. Records of the Western Australian Museum Supplement 77: 221–255.
[MM14] Moore, G. I., S. M. Morrison, J. B. Hutchins, G. R. Allen & A. Sampey. 2014. Kimberley marine biota. Historical data: fishes. Records of the Western Australian Museum Supplement 84: 161–206.
[M58] Munro, I. S. R. 1958. The fishes of the New Guinea region: A check-list of the fishes of New Guinea incorporating records of species collected by the Fisheries Survey Vessel “Fairwind” during the years 1948 to 1950. Papua and New Guinea Agricultural Journal 10 (4): 97–369 (reprinted: 1958. Territory of Papua and New Guinea Fisheries Bulletin no. 1).
[ND13] Near, T. J., A. Dornburg, R. I. Eytan, B. P. Keck, W. L. Smith, K. L. Kuhn, J. A. Moore, S. A. Price, F. T. Burbrink, M. Friedman & P. C. Wainwright. 2013. Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes. Proceedings of the National Academy of Sciences of the USA 110 (31): 12738–12743.
[P93] Patterson, C. 1993. Osteichthyes: Teleostei. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 621–656. Chapman & Hall: London.
[S66] Smith, J. L. B. 1966. Fishes of the sub-family Nasinae with a synopsis of the Prionurinae. Ichthyological Bulletin 32: 635–682.
[TB99] Tang, K. L., P. B. Berendzen, E. O. Wiley, J. F. Morrissey, R. Winterbottom & G. D. Johnson. 1999. The phylogenetic relationships of the suborder Acanthuroidei (Teleostei: Perciformes) based on molecular and morphological evidence. Molecular Phylogenetics and Evolution 11 (3): 415–425.
[WM93] Winterbottom, R., & D. A. McLennan. 1993. Cladogram versatility: evolution and biogeography of acanthuroid fishes. Evolution 47: 1557–1571.