Mustard Guttatus Tang
Mustard Guttatus Tang
Goes well with:
FAQs Answers to the most common questions.
Is a Mustard Guttatus Tang the same as Acanthurus guttatus, and what should I expect from its adult size and shape?
Yes—hobbyists usually mean Acanthurus guttatus, commonly called the Whitespotted Tang or sometimes a “mustard” variant due to its yellowish body tone. Expect a deep-bodied, laterally compressed surgeonfish that gets fairly large, commonly around 8–10 inches as an adult, with juveniles looking much smaller and more patterned. It is an active swimmer and needs long horizontal swimming space more than just height.
What tank size and aquascape does a Mustard Guttatus Tang need to stay healthy and reduce aggression?
For a single adult, I’d treat 125 gallons as a bare minimum, with 180 gallons or larger being much better long term. They need strong flow, high oxygenation, and open swimming lanes with substantial rockwork for grazing and retreat. Use porous live rock with established algae growth, but avoid making the tank so packed that it blocks cruising space. They can be territorial, especially toward other tangs and similarly shaped fish.
What should I feed a Mustard Guttatus Tang, and how often should it be fed to prevent HLLE or weight loss?
This tang should get a diet built around marine algae and high-quality herbivore foods: nori, spirulina-based pellets, frozen herbivore blends, and occasional mysis or other meaty foods in small amounts. Feed at least 2–3 times daily if possible, especially for juveniles and newly imported fish. Consistent vegetable matter is important for body condition and gut health, and a varied diet helps reduce nutritional problems like HLLE.
How aggressive is a Mustard Guttatus Tang, and can it be kept with other tangs or surgeonfish?
It can be moderately to very aggressive, especially as it matures or if kept in a smaller tank. It usually does best as the only tang unless the system is large and the introduction strategy is carefully managed. In bigger tanks, it may coexist with tangs from different body shapes or colors, but pairing it with similar Acanthurus species can trigger chasing and territorial disputes. Adding it last is usually a bad idea if it’s the most territorial fish in the tank.
What are the most common health issues in Mustard Guttatus Tangs, and how do I acclimate one safely from collection stress?
The biggest issues are shipping stress, ich/other parasites, fin fraying from aggression, starvation in new imports, and lateral line erosion/HLLE if the diet or water quality is poor. They often arrive thin and need immediate access to algae-rich foods. Acclimate them slowly, keep salinity and temperature stable, and put them into a mature tank with strong oxygenation and low stress. A quarantine period with observation is strongly recommended because tangs are parasite-prone and can crash quickly if weakened.
All listed sizes are approximate, not guaranteed, and may vary slightly.
The Mustard Guttatus Tang (Acanthurus guttatus), also known as the Whitespotted Surgeonfish, is a striking Indo-Pacific saltwater fish recognized for its deep-bodied profile and distinctive patterning. Adults typically display a gray-brown to olive body with pale vertical bands across the front half, numerous small white spots covering the rear body and fins, and bright yellow pelvic fins. Subtle mustard and bronze tones can become especially noticeable under strong reef aquarium lighting.
Native to shallow, high-energy reef flats and seaward reefs throughout the Indo-Pacific, this species is naturally adapted to areas exposed to strong surge and water movement. It spends much of the day grazing algae from hard reef surfaces, making it a natural fit for mature marine aquariums with established rockwork.
The Mustard Guttatus Tang is best suited to a large reef aquarium or fish-only aquarium with excellent oxygenation, strong filtration, and generous swimming space. Its active behavior, unusual coloration, and constant grazing make it an impressive display fish for appropriately sized systems.
Quick Care Guide
Care Level: Moderate
Minimum Tank Size: 180 gallons
Temperament: Semi-aggressive
Diet: Herbivore
Reef Safe: Yes
Region: Indo-Pacific
Scientific Name: Acanthurus guttatus
Tank Requirements
Provide a spacious aquarium with long, open swimming lanes and mature live rock arranged to create abundant grazing surfaces, caves, and sheltered resting areas. The aquascape should remain open enough for this active surgeonfish to move freely without being confined by dense rockwork.
Strong water movement is especially appropriate for this species because it naturally inhabits shallow reef environments exposed to surge and currents. Excellent oxygenation, efficient biological filtration, and consistently stable water quality are important for long-term success.
No specialized substrate is required. Mature rockwork with natural algae growth is highly beneficial, allowing the fish to graze between scheduled feedings. A secure aquarium cover is recommended because startled tangs can make sudden, powerful movements and may jump.
Diet and Feeding
The Mustard Guttatus Tang is primarily herbivorous and naturally grazes filamentous and other reef-associated algae from hard surfaces throughout the day.
Offer dried marine algae or nori regularly, along with spirulina-based pellets, high-quality herbivore pellets, marine algae preparations, and frozen herbivore blends. Mysis shrimp, enriched brine shrimp, and other small marine foods can be offered occasionally for variety, but vegetable-based foods should remain the foundation of the diet.
Several smaller feedings throughout the day are ideal when practical. Keeping algae sheets available for extended grazing helps support the species' natural feeding behavior.
Temperament and Tankmates
This species should be considered semi-aggressive, particularly around other tangs and surgeonfish. Territorial behavior is most likely toward similarly shaped species and other members of the genus Acanthurus competing for the same swimming and grazing areas.
Keeping a single specimen is the safest choice for most home aquariums. Multiple tangs should only be considered in substantially larger systems with extensive swimming space, multiple grazing zones, and carefully planned introductions.
Suitable tankmates include many wrasses, clownfish, anthias, chromis, rabbitfish, angelfish, and other appropriately sized marine fish that are not excessively aggressive.
Reef Compatibility
Reef Safe: Yes
The Mustard Guttatus Tang is considered reef safe and primarily grazes algae rather than feeding on corals or ornamental invertebrates. It is generally suitable for established reef aquariums containing soft corals, stony corals, clams, ornamental shrimp, crabs, and snails.
Its grazing activity can be beneficial in a reef aquarium, but regular supplemental feeding is still essential even when natural algae is present.
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 and avoid rapid changes in temperature, salinity, or pH. Consistency is more important than targeting a single exact number within these ranges.
Common Considerations
-
Requires a large aquarium with substantial open swimming space.
-
Benefits from strong water movement and excellent oxygenation.
-
Needs frequent access to marine algae and other vegetable-rich foods.
-
May become territorial toward other tangs, especially similarly shaped Acanthurus species.
-
Possesses sharp scalpel-like spines near the base of the tail, so care should be taken during capture and transfer.
