Convict Tang (Acanthurus Triostegus)

Also Known As: Convict Surgeonfish
Compatibility and Behavior
The Convict Tang (Acanthurus triostegus) is one of those fish that earns its name the moment you see it. A soft, silvery-white to pale green body crossed by six bold vertical black bars gives it that unmistakable prison-stripe look, and it stands out cleanly against live rock and coral. Add a streamlined profile, a narrow head, and translucent fins, and you get a fish with a tidy, minimalist appearance that's all the more striking for how understated it is. Behavior is where this tang really sets itself apart from its relatives. It tends to be noticeably more peaceful than most Acanthurus species, and in very large tanks it's often kept in small groups or loose shoals where you can watch natural grazing and schooling play out. They're generally considered reef safe, spending the bulk of the day picking film and filamentous algae off rock and glass rather than bothering corals or inverts. They may posture a bit toward other tangs, particularly similar Acanthurus, but in most cases they're far milder than their cousins and coexist nicely with community fish like clownfish, wrasses, chromis, and Anthias when there's room to spread out.
Aquarium Requirements
Convict Tangs do best in larger, established systems with long swimming runs and plenty of mature live rock to graze. A tank in the 120 to 180 gallon range or up works well, and you'll want the larger end of that if you're keeping more than one. Aquascape with open cruising lanes paired with rockwork that forms arches, ledges, and safe retreats, so they can move freely while still feeling secure. Strong, well-oxygenated flow and solid filtration matter here, since this is a busy herbivore that does best in clean, stable water with frequent feedings of dried marine algae and nori. A tight-fitting lid or mesh top is a good idea too, because a startled tang can dart fast and may go airborne if spooked.

Specifications
Approximate Size: Sm: 1.5–2.5", Md: 2.5–3.5", Lg: 3.5–4.5", XL: 4.5–6"
Diet: Primarily herbivorous. Film and filamentous algae, nori, spirulina-based foods
Origin: Indo-Pacific, including Hawaii, the central Pacific, and Indian Ocean reefs
Care Level: Intermediate
Reef Safe: Generally reef safe; focuses on algae rather than corals or inverts
Temperament: Peaceful to semi-aggressive; mild for a tang, but may spar with similar species
Minimum Tank Size: Smaller specimens (Sm/Md) can start around 75–90 gallons, but plan to scale up to 120 gallons or more as they grow, especially if keeping more than one
Special Considerations: Best in a mature, stable system with strong filtration and ample algae