QUICK STATS

Care Level: Moderate
Diet: Herbivore / Omnivore
Temperament: Peaceful
Reef-Safe: With Caution
Venomous/Toxic: Yes
Approximate Purchase Size: 2-4"
Approximate Max Size: Around 10"
Recommended Tank Size: 100-125 Gallons or Larger

BICOLOR FOXFACE

The Bicolor Foxface (Siganus uspi) is a striking rabbitfish known for its bold two-tone coloration, peaceful personality, and strong algae-grazing behavior. Its front half is typically darker, often black or deep brown, while the rear portion is bright yellow, giving it a clean split-color appearance that stands out beautifully in larger reef aquariums.

Bicolor Foxfaces are generally peaceful fish that spend much of their day grazing across rockwork, picking at algae, and cruising through open swimming space. They are especially useful in established aquariums where natural algae growth is available, though they should still be fed a varied diet rich in algae-based foods.

This species is considered reef-safe with caution. Most individuals leave corals alone when well fed, but underfed rabbitfish may occasionally pick at soft corals, LPS, sponges, tunicates, or other sessile invertebrates. So yes, it is helpful, beautiful, and mostly polite, but still technically a fish with a mouth and poor legal accountability.

Bicolor Foxfaces also have venomous dorsal and anal spines used for defense. They do not attack people with them, but care should be taken during tank maintenance, catching, or transfer. In other words: peaceful fish, spicy fins. Naturally.

Note: Image is a representation of what to expect. The fish you receive may vary slightly in size, color, pattern, and overall appearance.

AQUARIUM REQUIREMENTS

AQUARIUM SIZE

A minimum tank size of 100-125 gallons or larger is recommended for a Bicolor Foxface. Although juveniles may be sold smaller, adults can reach around 10 inches and need plenty of swimming room.

A larger aquarium also provides more grazing surface, better water stability, and more space for the fish to settle without feeling crowded. This is not a tiny nano-tank algae intern. It is a large rabbitfish with a schedule.

HABITAT RECOMMENDATIONS

Bicolor Foxfaces do best in mature aquariums with open swimming space, live rock, and low-stress surroundings.

Aquascaping: Provide a mix of open swimming room and live rock for grazing, resting, and hiding. Foxfaces often retreat to rockwork when startled or stressed.

Substrate: Sand or fine aragonite works well and helps create a natural reef-style environment.

Rockwork: Live rock is strongly recommended. It gives the fish grazing surfaces and places to hide when nervous.

Tank Maturity: A mature aquarium is preferred, especially one with natural algae and biofilm growth. These fish are excellent grazers, but they still need regular supplemental feeding.

Tank Cover: A tight-fitting lid is recommended. Foxfaces are not the worst jumpers, but large startled fish can still make large regrettable decisions.

WATER PARAMETERS

Bicolor Foxfaces are generally hardy once established, but they still need clean, stable marine conditions. “Hardy” does not mean “immune to aquarium nonsense,” a lesson humanity keeps paying for in saltwater.

Temperature: 74-80°F
pH Level: 8.1-8.4
Salinity: 1.020-1.026 specific gravity
Ammonia, Nitrite, and Nitrate: Ammonia and nitrite should remain undetectable. Nitrate should be kept as low as reasonably possible, ideally below 20 ppm.
Water Flow: Moderate water movement is ideal. Provide enough flow to keep the aquarium oxygenated and move waste toward filtration, while still allowing calmer areas for resting and grazing.

DIET

Bicolor Foxfaces are primarily herbivorous grazers, though they will also accept a variety of omnivore foods. A diet rich in algae-based foods is important for maintaining body condition, color, and long-term health.

PRIMARY DIET

Frozen Food: Offer algae-rich frozen foods, mysis shrimp, enriched brine shrimp, marine blends, and other high-quality frozen foods. We at Summit City Coral prefer frozen foods such as LRS Herbivore Frenzy and PE Mysis.

Prepared Herbivore Foods: High-quality herbivore pellets, flakes, and marine algae blends can help provide a balanced diet.

Algae-Based Foods: Nori, spirulina, seaweed sheets, herbivore blends, and algae wafers should be included regularly. Clip seaweed sheets to the glass or rockwork so the foxface can graze naturally.

Natural Grazing: Established live rock with film algae, turf algae, and biofilm can help support natural feeding behavior. This does not mean the foxface should be expected to fix an algae disaster alone, because fish are livestock, not unpaid maintenance contractors.

FEEDING FREQUENCY

Feed small amounts 1-2 times per day, with algae-based foods offered regularly. Foxfaces are active grazers and do best when they have frequent access to plant-based nutrition.

COMPATIBILITY

Bicolor Foxfaces are generally peaceful and work well in larger community aquariums. They can often be kept with a variety of peaceful and semi-aggressive fish due to their size and defensive venomous spines.

COMMON TANK MATES

Fish: Clownfish, tangs, wrasses, cardinalfish, gobies, blennies, dwarf angelfish, larger peaceful fish, and other community reef fish.

Avoid: Other rabbitfish or similarly shaped algae grazers in smaller aquariums unless the tank is large enough to provide space and reduce competition. Avoid aggressive fish that may harass or stress the foxface.

Invertebrates: Usually safe with most cleaner shrimp, hermit crabs, snails, urchins, and common cleanup crew animals.

Coral: Bicolor Foxfaces are considered reef-safe with caution. Most individuals behave well in reef tanks, especially when fed properly, but some may nip at soft corals, LPS, sponges, tunicates, or other sessile invertebrates.

BEHAVIORAL NOTES

Temperament: Peaceful overall and usually calm with tank mates.

Venomous Spines: Bicolor Foxfaces have venomous dorsal and anal spines used for defense. Use caution during tank maintenance, catching, or transfer. Avoid grabbing or netting carelessly unless you enjoy turning aquarium chores into medical paperwork.

Algae Grazing: Excellent grazer for film algae, soft algae, and some nuisance algae. Still requires regular feeding and should not be used as the entire algae-control plan.

Color Change: Foxfaces may show darker, blotchy, or camouflaged coloration when stressed, sleeping, or frightened. This is normal and usually resolves once the fish feels secure.

Reef Compatibility: Usually good in reef aquariums, but best listed as reef-safe with caution due to possible coral or invertebrate nipping.

Territoriality: Usually peaceful, but may show aggression toward other rabbitfish or similarly shaped fish.

Handling: Avoid direct contact with the spines. Use a container when transferring when possible.

Jumping: A tight-fitting lid is recommended. Even large peaceful fish can become airborne idiots when startled.

ACCLIMATION PROCESS

This acclimation method helps reduce stress by gradually introducing the fish to your aquarium’s temperature and water chemistry.

1. TURN OFF THE LIGHTS & ATO

Turn off aquarium lights to reduce stress. If you have an Auto Top Off system, switch it off before starting acclimation.

2. FLOAT THE BAG

Float the sealed bag in the aquarium for 15-20 minutes to allow the temperature in the bag to equalize with the tank.

3. OPEN BAG, ADD FISH TO CONTAINER

Carefully open the bag and transfer the fish and shipping water into a clean bucket or container.

4. ACCLIMATE USING TANK WATER

Add 1/4 cup of tank water to the container every 5 minutes for 40 minutes.

5. TRANSFER FISH TO AQUARIUM

Once acclimation is complete, gently transfer the fish into the aquarium using a specimen container when possible. Use caution around the venomous dorsal and anal spines. Discard the shipping water. Do not pour shipping water into your aquarium.

6. REFILL THE AQUARIUM WITH SALTWATER

You may need to replace the saltwater removed during acclimation with fresh mixed saltwater.