Acanthurus triostegusFiveband surgeonfish

Geographic Range

Convict tangs are found throughout the Indo-Pacific region, as well as the eastern Pacific Ocean from the lower Gulf of California to Panama. They are also known as convict surgeonfish or Manini. (Froese and Pauly, 2011; Lecchini and Galzin, 2005)


Convict tangs are surgeonfish that prefer to occupy coral reefs, but are also found in tidepools and other nearshore habitats such as shallow, low current beach communities. They are tropical reef fish whose latitudinal range is 26ºN to 36ºS with a longitudinal range from 25ºE to 85ºW. Convict tangs are mainly found in temperatures ranging from 24-26ºC and at depths of 0-90 m. (Education Department Waikiki Aquarium, 2012; Fauvelot and Planes, 2002; Froese and Pauly, 2011; Lecchini and Galzin, 2005)

  • Range depth
    90 to 0 m
    295.28 to 0.00 ft

Physical Description

Convict tangs have a pale body color varying from white/greenish-white to gray or even yellow. This background is overlaid with distinct, vertical black stripes, including one going through each eye. They are highly laterally compressed and have small scales, gill rakers, dorsal spines and anal spines. Their average length is 17.0 cm, with a maximum length of 27.0 cm. ("Convict Tang - Acanthurus triostegus", 2012; Education Department Waikiki Aquarium, 2012; Fishelson, 1999; Froese and Pauly, 2011; Kiflawi and Mazeroll, 2006)

  • Range length
    27.0 (high) cm
    10.63 (high) in
  • Average length
    17.0 cm
    6.69 in


Convict tang eggs hatch into clear pelagic larvae. In Hawaiian populations it takes about 2.5 months for these planktonic larvae to develop into juveniles in a reef or tidepool; larvae typically adapt to their benthic surroundings within 24 hours. Initially, juveniles lack the vertical bars present in adults. (Education Department Waikiki Aquarium, 2012; Nakamura, et al., 2009)


Convict tangs spawn in resident spawning aggregations. Spawning groups can be as large as tens of thousands of fish with subgroups of 10-20 fish, although pair spawning has also been observed. Research in Hawaii showed that individuals may migrate up to 2 km to reach spawning sites on the seaward side of a reef or in channels connecting lagoons to open ocean. (Domeier and Colin, 1997)

Convict tang populations near the equator can spawn at any time during the year, while populations elsewhere may only spawn seasonally (in Hawaii spawning occurs around full moons in February and March). (Eble, et al., 2009; Education Department Waikiki Aquarium, 2012; Froese and Pauly, 2011)

  • Breeding interval
    Convict tangs breed annually.
  • Breeding season
    Spawning can occur year round in equatorial habitats and seasonally in other parts of the range.

Convict tangs are broadcast spawners and provide no parental investment to offspring. (Froese and Pauly, 2011)

  • Parental Investment
  • no parental involvement


Convict tangs have a typical lifespan of 5-7 years in captivity. Their average lifespan in the wild is currently unknown. ("Convict Tang - Acanthurus triostegus", 2012)

  • Range lifespan
    Status: captivity
    5 to 7 years
  • Typical lifespan
    Status: captivity
    5 to 7 years


Convict tangs are often found in schools (large and small) but may also be found individually. While less territorial than other tangs, tank size is still an important consideration for those keeping this species. Convict tangs have been observed in the wild exhibiting tonic immobility (death feigning). ("Convict Tang - Acanthurus triostegus", 2012; Education Department Waikiki Aquarium, 2012; Howe, 1992; Reebs, 2007)

Home Range

There is currently no published information regarding the home range or territory size of Convict tangs.

Communication and Perception

Convict tangs are able to perceive their environments through a number of sensory pathways, including sight, olfaction, sound and vibrations (detected by their lateral lines). Information regarding which of these senses are important in intra- and interspecific communication is currently unavailable. (Bond, 1996)

Food Habits

Convict tangs are herbivores, grazing on algae found on rocks and corals. Adaptations to their algivorous diet include mouths that are slightly downwardly-directed and flexible, comb-like teeth. (Education Department Waikiki Aquarium, 2012; Froese and Pauly, 2011)

  • Plant Foods
  • algae


Convict tangs have been observed exhibiting tonic immobility, which may be a response to the presence of a predator. As with other surgeonfishes, they have sharp blades on either side of the tail; however, these blades are poorly developed in convict tangs and not typically used for defense. Instead, this species relies on traveling in large schools, as well as its disruptive color pattern, for protection. Although undoubtedly not a complete list of predators, convict tangs are known to be preyed upon by argus grouper, ash-colored conger eel, honeycomb grouper, cornet fish, and black-tail snapper. Eagle rays are also known to feed on convict tang gametes during spawning. (Education Department Waikiki Aquarium, 2012; Froese and Pauly, 2011; Reebs, 2007)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The grazing of convict tangs on algae helps keep algal populations in check. Convict tangs also host symbiotic unicellular organisms in their gut, including one of the largest known bacterial species (Epulopiscium fishelsoni). Convict tangs are host to endoparasitic nematodes and trematodes, as well as at least one ectoparasitic copepod species. (Arthur and Lumanlan-Mayo, 1997; Education Department Waikiki Aquarium, 2012; Fishelson, 1999; Lewis, 1964; Rigby and Adamson, 1997)

Mutualist Species
  • Epulopiscium fishelsoni (Class Clostridia, Kingdom Bacteria)
Commensal/Parasitic Species
  • Spirocamallanus colei (Class Secernentea, Phylum Nematoda)
  • Hysterolecitha acanthuri (Class Trematoda, Phylum Platyhelminthes)
  • Caligus flexispina (Subclass Copepoda, Subphylum Crustacea)

Economic Importance for Humans: Positive

Convict tangs are part of the human diet in tropical regions. They are also sold in the aquarium trade. (Froese and Pauly, 2011)

Economic Importance for Humans: Negative

There have been reports of humans suffering from ciguatera poisoning after consuming convict tangs, although the species is generally considered safe to eat. (Froese and Pauly, 2011; Halstead, et al., 1990)

Conservation Status

Convict tangs currently have no special conservation status.

Other Comments

Genetic studies on Polynesian populations of convict tangs indicate that, despite the pelagic larval stage, most populations exhibit limited recruitment through dispersal. (Bresler, et al., 1998; Fishelson, 1999)

The large bacterium Epulopiscium fishelsoni was first isolated from the gut of brown surgeonfish (A. nigrofuscus); similar morphotypes, collectively called "euplos", have since been found in other surgeonfish species, including convict tangs. Euplo morphotypes found in convict tangs are 20 times longer than they are wide, which is much longer and thinner than those found in other species of surgeonfish. (Planes, et al., 1994)


Rex Gamoke (author), Sierra College, Jennifer Skillen (editor), Sierra College, Jeremy Wright (editor), University of Michigan-Ann Arbor.


Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map


uses sound to communicate


Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


A substance that provides both nutrients and energy to a living thing.


An animal that eats mainly plants or parts of plants.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

pet trade

the business of buying and selling animals for people to keep in their homes as pets.


an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate

year-round breeding

breeding takes place throughout the year


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