Lavender Tang

The Lavender Tang (Acanthurus nigrofuscus), also known as the Brown Surgeonfish or Spot-Cheeked Surgeonfish, is an attractive Indo-Pacific saltwater fish prized for its subtle coloration and active grazing behavior. Adults typically display an olive-brown to lavender-gray body accented by fine bluish lines, colorful orange to yellow spotting across the face, blue-edged fins, and distinctive dark markings near the bases of the dorsal and anal fins. Its understated coloration becomes especially attractive under quality reef aquarium lighting. Native to shallow lagoon and seaward reefs throughout a broad Indo-Pacific range, this species spends much of the day moving across hard reef surfaces in search of filamentous algae. Its relatively compact adult size compared with some surgeonfish makes it appealing for appropriately sized marine aquariums, although it remains an energetic tang that requires substantial swimming room. With mature rockwork, strong water quality, and a diet rich in marine algae, the Lavender Tang can make an excellent addition to a large reef aquarium or fish-only aquarium. Its temperament is generally manageable with unrelated species, but territorial behavior toward other tangs and surgeonfish should be expected. Quick Care Guide Care Level: Moderate Minimum Tank Size: 125 gallons Temperament: Semi-aggressive Diet: Herbivore Reef Safe: Yes Region: Indo-Pacific, from the Red Sea and East Africa east through the central Pacific, including Hawaii and the Tuamotu Islands Scientific Name: Acanthurus nigrofuscus Tank Requirements Provide a spacious aquarium with plenty of open swimming room and mature live rock arranged to create grazing surfaces, caves, and sheltered resting areas. Rockwork should be positioned so the fish can move freely around and between structures rather than being confined by a densely packed aquascape. Moderate to strong water movement, excellent oxygenation, and efficient biological filtration are recommended. Established live rock with natural algae growth is particularly beneficial, allowing the fish to graze throughout the day between regular feedings. No specialized substrate is required. A secure aquarium cover is recommended because tangs can make sudden, powerful movements when startled, particularly during acclimation or territorial encounters. Diet and Feeding The Lavender Tang is primarily herbivorous and naturally feeds heavily on filamentous algae growing across reef surfaces. Captive feeding should emphasize marine vegetable matter to support healthy body condition and natural grazing behavior. Offer dried marine algae or nori frequently, along with spirulina-based pellets, high-quality herbivore pellets, marine algae preparations, and frozen herbivore blends. Mysis shrimp, enriched brine shrimp, and other marine proteins can be offered occasionally as supplemental foods, but the diet should remain predominantly algae-based. Several smaller feedings throughout the day are beneficial when practical. Keeping algae sheets available for extended grazing helps replicate the frequent feeding pattern of wild surgeonfish. Temperament and Tankmates The Lavender Tang is generally compatible with peaceful to moderately assertive community fish but can become territorial toward other tangs. Aggression is most likely toward similarly shaped surgeonfish, particularly other members of the genus Acanthurus competing for the same swimming and grazing areas. A single specimen is the safest option for most aquariums. Keeping multiple tangs requires considerably more space, abundant feeding opportunities, multiple territories, and carefully planned introductions. Suitable tankmates include many clownfish, wrasses, anthias, chromis, gobies, rabbitfish, angelfish, and other appropriately sized marine species. Avoid pairing it with highly aggressive fish that may prevent it from feeding or settling into the aquarium. Reef Compatibility Reef Safe: Yes The Lavender Tang is considered reef safe and normally directs its grazing behavior toward algae rather than corals or ornamental invertebrates. It is generally suitable for established reef aquariums containing soft corals, stony corals, clams, ornamental shrimp, crabs, and snails. Its regular grazing can be useful in a reef aquarium, but the fish should receive abundant supplemental algae rather than being expected to live entirely on algae growing naturally in the system. Water Parameters Temperature: 75–80°F Specific Gravity: 1.024–1.026 pH: 8.1–8.4 Alkalinity: 8–12 dKH Maintain stable, well-oxygenated water with consistent salinity, temperature, and pH. Long-term stability is more important than attempting to maintain a single exact value within these ranges. Common Considerations Requires substantial open swimming space despite being smaller than many other surgeonfish. Needs frequent access to marine algae and other vegetable-rich foods for proper long-term nutrition. May become territorial toward other tangs, especially similarly shaped Acanthurus species. Benefits from mature live rock that provides continuous natural grazing opportunities. Possesses sharp scalpel-like spines near the base of the tail, so care should be taken during capture and transfer.