Orangeshoulder Tang (Acanthurus olivaceus)

The Orangeshoulder Tang is a striking and graceful species, known for the distinctive orange spot on its shoulder and its overall transformation from juvenile to adult coloration. Juveniles are primarily yellow, while adults display a more subdued olive-gray body with the signature orange spot. This tang is active, peaceful, and an excellent algae grazer, making it a beneficial and visually appealing addition to large reef or fish-only tanks.

Care Information

• Maximum Size: Up to 14 inches.
• Tank Size: 180 gallons minimum; a spacious tank with ample swimming space and live rock for grazing is essential due to the tang's large size and active swimming behavior.
• Diet: Herbivorous; primarily feeds on algae and should be offered a diet rich in marine-based seaweed, algae, and high-quality herbivore pellets. Supplementing with fresh greens such as nori will help maintain their health.
• Water Temp: 74-80°F.
• Salinity: 1.020-1.025.
• Aggression: Generally peaceful, but may become territorial with other tangs, especially in smaller tanks. Best kept with similarly sized, non-aggressive tankmates in a large aquarium.
• Skill Level: Intermediate to Advanced; requires stable water conditions and a well-balanced diet.
• Reef Compatibility: Reef-safe; does not harm corals or invertebrates and helps control algae growth in reef tanks.

Special Feature - Color Transformation
One of the most fascinating aspects of the Orangeshoulder Tang is its dramatic color transformation. Juveniles are bright yellow with subtle markings, while adults develop an olive-gray body with a distinct orange shoulder patch, making it one of the most visually striking tang species. This transformation adds an extra layer of interest for aquarists.

Coloration

• Indo-Pacific Region: As juveniles, Orangeshoulder Tangs are predominantly yellow with faint markings. As they mature, they develop their iconic orange shoulder spot and an olive-gray body, along with blue highlights along their fins. This transition in coloration makes them a visually dynamic fish in any tank​.

Typical Habitat

• Distribution: The Orangeshoulder Tang is native to the Indo-Pacific, particularly around the waters of the Philippines, Indonesia, and Hawaii. It inhabits coral reefs and coastal areas, where it grazes on algae along reef slopes​.