Species Details

Details of Convict Surgeonfish will be displayed below

Convict Surgeonfis...   

Common Name: Convict Tang, Fiveband Surgeonfish
Scientific Name: Acanthurus triostegus
Local Name: Raa'bulhaa
Dhivehi Name: ރާބުޅާ
Animalia  (Kingdom)
Chordata  (Plylum)
Perciformes  (Order)
Acanthuridae  (Family)
Acanthurus   (Genus)

Convict Surgeonfish's description

Convict surgeonfish (Acanthurus triostegus) is a small surgeonfish in family Acanthuridae of the order Perciformes. It is typically about 10 cm (3.9 in) long, but some individuals may grow larger than 20 cm. Dorsal spines (total): 9; Dorsal soft rays (total): 22-26; Anal spines: 3; Anal soft rays: 19 - 22. Body olivaceous gray, with 4 vertical stripes (1 stripe on head across the yellow eye; 1 on caudal peduncle); shading to white ventrally, often with a sharp line of demarcation. Sharp, forward-pointing, erectile spine on each side of caudal peduncle which folds down into a groove. Scales minute. Teeth with denticulations on sides and top. Gill rakers 18-22 in anterior row, 19-24 in posterior row.

Convict Surgeonfish's facts

Did you know?

  • Convict surgeonfish is a very common species in the Maldives. This species is of little interest
    among aquarists.

Convict Surgeonfish's Behavior & Ecology

Distributed in indo-Pacific and Eastern Pacific. Adults occur in lagoon and seaward reefs with hard substrate; young abundant in tide pools. 

Convict Surgeonfish's Feeding

Benthopelagic. Often feeding near where certain algae grow on rocks that are grazed. Occasionally form schools; feed on filamentous algae in large aggregations.

Convict Surgeonfish's Reproduction

During spawning, clouds of eggs and sperm are preyed upon by eagle rays which are often present during spawning. Form spawning aggregations. 

Convict Surgeonfish's Relationship with Humans

Utilized as a food fish.

Convict Surgeonfish habitat

 This reef-associated species occurs in lagoons and seaward reefs with hard substrate. It is usually seen in reef crests in shallow exposed reef fronts (J.H. Choat pers. comm. 2010). The young are abundant in tide pools (Randall 1986, Kuiter and Tonozuka 2001) In the Gulf of Chiriqui, Panama, this species can be found over zones of madreporic branching corals, in sheltered areas (Dominici-Arosemena and Wolff 2006). In Hawaii, this species occurs in bays, harbours, and exposed reef areas. It abounds in tide pools and shallow water, yet is also known in depths of at least 100 ft (Randall 1961b). It is often observed feeding near freshwater run-offs where certain algae grow on rocks (Kuiter and Tonozuka 2001). Adults are often observed in large feeding aggregations, it may also be seen as solitary or in small groups. Large aggregations may be dense and cover areas more than 50 ft in diameter (Randall 1961b). It feeds on algal turfs (Choat et al. 2004).  It is classified as a grazer (Green and Bellwood 2009).
It rarely achieves sizes above 20 cm (TL).


The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010). This species spawns year-round in equatorial waters, but seasonally in Hawaii, coinciding with the colder part of the year (February-March) (Randall 1961b). It recruits year-round in Guam (J. McIlwain unpub. data).

It was observed to form spawning aggregations on the Great Barrier Reef (Randall 1961a, 1961b; Johannes 1981; Robertson 1983). In Palau it spawns from May-August after the new moon (Randall 1961b). At Aldabra Atoll it spawns from November-December (Robertson 1983). During midday to dusk fish migrate in dense streams to aggregation sites, reaching tens of thousands to spawn (Randall 1961a, 1961b; Robertson 1983; Randall et al. 1990). Males displayed a spawning colour phase. Spawning takes place in pulses by sub-groups of 10-20 fish (Randall 1961a, 1961b; Robertson 1983). Pair spawning has also been observed in this species. A. triostegus aggregations are resident spawning aggregations (Domeier and Colin 1997). Its size during metamorphosis, from the post-larval stage to juvenile, is 3.2 cm (Krupp 1995). The eggs and larvae are pelagic. The smallest running ripe female found on Oahu was 10.1 cm (SL); the smallest male 9.7 cm (SL) (Randall 1961b).

Convict Surgeonfish threats

Localized fishing for artisanal and recreational fisheries is a threat in some areas.

Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).

Convict Surgeonfish's status