Convict Tang (Acanthurus triostegus)

The Convict Tang, also known as the Manini in Hawaii, is a sleek and energetic member of the Surgeonfish family. While it lacks the neon colors of some of its cousins, it is highly prized for its crisp, clean aesthetic and its reputation as one of the hardest-working algae eaters in the hobby. In the wild, they are famous for forming massive "super-schools" that overwhelm reef territories to graze on lush algae beds.

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Key Information

• Common Names: Convict Tang, Convict Surgeonfish, Manini

• Scientific Name: Acanthurus triostegus

• Origin: Widespread Indo-Pacific and Eastern Pacific

• Max Size: 20 cm (approx. 8 inches)

• Lifespan: 7–10+ years

• Temperament: Peaceful; one of the least aggressive Acanthurus species

• Diet: Herbivore – A relentless grazer of hair algae and films

• Care Level: Moderate (Requires high oxygen and frequent feeding)

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Appearance & Identification

The Convict Tang is defined by its striking "uniform":

• Pattern: A silver-to-creamy white body marked by six vertical black bars.

• Fins: The dorsal and anal fins often have a faint yellow-green tint.

• The "Scalpel": Like all tangs, it has a sharp, retractable spine at the base of its tail (the caudal peduncle) for defense, though it is less conspicuous on this species.

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Behaviour & Tank Compatibility

• The Workhorse: If you have a nuisance hair algae problem, the Convict Tang is often more effective than many "clean-up crew" invertebrates. They spend almost every waking second picking at the rocks.

• Schooling Potential: Unlike most tangs (which are solitary and fight their own kind), Convict Tangs are highly social. In very large systems (500L+), they can be kept in groups of 3 or more, which creates a stunning schooling display.

• Peaceful Nature: They are generally very docile toward other fish. However, because they are peaceful, they can be bullied by more aggressive tangs like the Powder Blue or Sohal.

• Reef Safe: 100% Reef Safe. They are excellent for coral health as they prevent algae from smothering polyps.

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Ideal Tank Setup

• Tank Size: A minimum of 285L (75 Gallons) is required for a single specimen, but 475L+ (125+ Gallons) is recommended for a group or to allow for their high-speed swimming.

• Oxygenation: They naturally inhabit surge zones and reef flats. They require high oxygen levels and strong water turnover.

• Swimming Space: They are "marathon swimmers." Ensure your rockwork provides plenty of open "lanes" for them to cruise at high speeds.

• Lid: They are active and fast; a jump is possible if they are startled at night. A secure lid is recommended.

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Dietary Needs

Because they have high metabolisms and are constant grazers, they can lose weight quickly:

• Continuous Grazing: Provide dried seaweed (Nori) on a clip daily.

• Variety: They should be offered a mix of spirulina-enriched flakes, pellets, and frozen herbivore preparations.

• Vitamin Supplementation: Soaking food in a vitamin supplement (like Selcon) helps prevent Head and Lateral Line Erosion (HLLE), which Acanthurus species can be prone to.