Orange Shoulder Tang (Acanthurus Olivaceus)

Also Known As: Orangeshoulder Surgeonfish

Compatibility and Behavior
The Orange Shoulder Tang (Acanthurus olivaceus) is a graceful, active grazer that works as a centerpiece without ever feeling flashy about it. One of the real treats with this species is the transformation: juveniles come through bright yellow with a soft gray face, then gradually shift into an elegant slate-gray to olive adult, with the namesake orange patch bordered in dark gray on the shoulder and a soft, powdery blue edging along the fins. Note: Small and sometimes Medium Orange Shoulders may be juvenile coloration. A lot of hobbyists keep this fish specifically to watch that change unfold in the display over time. As for temperament, the Orange Shoulder is often counted among the more mild-mannered Acanthurus tangs, and it tends to coexist well with a broad range of community fish when there's enough room to go around. It's generally regarded as reef safe, spending most of the day grazing film and filamentous algae off rock and hard surfaces rather than picking at corals or ornamental inverts. That said, like any tang, it can get more assertive toward other tangs or similarly shaped herbivores in tight or crowded quarters, so thoughtful stocking and plenty of open swimming room go a long way toward keeping the peace.

Aquarium Requirements
Orange Shoulder Tangs can grow large and want room to stretch out, so they're best kept in roomy, established systems. You can start at around 90 gallons for a small one, but a long tank in the 150-gallon-plus range is ideal to sustain eventual growth. Give them open lanes for cruising alongside substantial mature live rock for grazing, plus a few secure caves or overhangs where they can retreat and rest. Strong, well-oxygenated flow and robust filtration support their active lifestyle and high oxygen demand, and a tight-fitting lid or mesh top is recommended, since a startled fish can jump. Regular feedings of nori sheets, spirulina-based foods, and mixed herbivore fare will keep them well nourished, help curb aggression, and support long-term health and color.

Specifications
Approximate Size: Sm: 1.5–2", Md: 2.5–3.5", Lg: 4–5"
Diet: Primarily herbivorous. Marine algae, nori, and spirulina-based foods, with supplemental frozen mysis shrimp
Origin: Indo-Pacific, including the central and western Pacific
Care Level: Intermediate
Reef Safe: Generally reef safe; focuses on algae and film growth rather than corals
Temperament: Peaceful to semi-aggressive; relatively mellow for an Acanthurus, but may show dominance toward other tangs in tight quarters
Minimum Tank Size: Small specimens can start around 90 gallons, but plan to scale up to 150 gallons or more as they grow
Special Considerations: Grows large and needs ample horizontal swimming room and strong filtration; a tight-fitting lid is advisable, as startled fish can jump