Bicolor Fiji Foxface

The Bicolor Fiji Foxface (Siganus uspi) is a striking rabbitfish prized for its bold two-tone coloration and distinctive fox-like profile. Its deep, laterally compressed body features a dramatic division between rich dark purplish-brown coloration across the front portion of the fish and a contrasting bright yellow posterior body and fins. This sharp color transition gives the species a sophisticated appearance unlike other commonly kept Foxface rabbitfish.

Native primarily to Fiji in the Western Pacific, this species inhabits coral reef environments, including reef edges, drop-offs, and deeper pools within reef crests. Juveniles may occur in groups, while adults are more commonly found in pairs. Like other rabbitfish, it spends much of its active period browsing seaweed and algae from reef surfaces.

Reaching approximately 9–10 inches as an adult, the Bicolor Fiji Foxface makes an impressive addition to a spacious reef aquarium or fish-only aquarium. Its generally peaceful temperament and natural algae-grazing behavior are highly desirable, although its venomous fin spines and potential interest in some sessile invertebrates require appropriate care.

Quick Care Guide

Care Level: Moderate
Minimum Tank Size: 125 gallons
Temperament: Peaceful
Diet: Herbivore
Reef Safe: With Caution
Region: Fiji, Western Pacific
Scientific Name: Siganus uspi

Tank Requirements

Provide a spacious aquarium with substantial open swimming room along with mature rockwork for grazing, shelter, and nighttime resting areas. Caves, ledges, and overhangs help the fish feel secure, particularly during its initial acclimation period.

Because this species develops a deep body and approaches approximately 9–10 inches in adult length, ample horizontal swimming space is important for long-term housing. Arrange rockwork so that natural grazing surfaces are abundant without restricting movement through the aquarium.

Moderate to strong water movement, efficient filtration, and consistently high water quality are recommended. A secure aquarium cover is also advisable, especially during acclimation when the fish may become easily startled.

Diet and Feeding

The Bicolor Fiji Foxface is primarily herbivorous and naturally feeds heavily on seaweeds. Marine algae should therefore form a major part of its captive diet.

Offer dried marine algae or nori regularly, ideally attached to a feeding clip where the fish can graze throughout the day. Supplement with spirulina-based foods, high-quality herbivore pellets, and frozen preparations designed for marine herbivores.

Mysis shrimp, enriched brine shrimp, and mixed frozen marine foods can be offered occasionally for additional dietary variety, but vegetable-based foods should remain the foundation of the diet. Feeding one to three times daily, combined with access to natural algae on established rockwork, helps maintain good body condition.

Temperament and Tankmates

The Bicolor Fiji Foxface is generally peaceful toward unrelated marine fish and can be housed with many community species. Suitable tankmates may include tangs, angelfish, clownfish, wrasses, anthias, gobies, and other peaceful to moderately assertive saltwater fish.

Territorial behavior is more likely toward other rabbitfish, particularly similarly shaped Foxface species. A single specimen is generally recommended unless an exceptionally large aquarium or a compatible established pair is available.

Like other rabbitfish, it may temporarily become darker or mottled when frightened, stressed, or resting. This rapid coloration change is normal behavior.

The dorsal and anal fin spines are venomous and are used defensively. The fish is not normally aggressive toward aquarists, but caution should be exercised when transferring it or working nearby in the aquarium.

Reef Compatibility

Reef Safe: With Caution.

The Bicolor Fiji Foxface can be successfully maintained in many reef aquariums and is particularly valued for its algae-grazing behavior. It generally poses little threat to ornamental shrimp, crabs, snails, and other mobile invertebrates.

Individual specimens may occasionally nip at soft corals, zoanthids, fleshy LPS corals, or other sessile organisms. Providing frequent access to marine algae and a varied herbivore-focused diet may reduce unwanted grazing, but complete coral safety cannot be guaranteed.

Water Parameters

Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Stable water quality is more important than maintaining one exact value within these ranges. Avoid rapid fluctuations in salinity, temperature, or pH, particularly during acclimation.

Common Considerations

• Reaches approximately 9–10 inches and requires substantial swimming space as an adult.

• Possesses venomous fin spines and should be handled with appropriate caution.

• Requires a vegetable-rich diet with regular access to marine algae or seaweed.

• May become territorial toward other Foxface and rabbitfish species.

• Generally suitable for reef aquariums with caution, as individual fish may occasionally nip at coral tissue or other sessile invertebrates.