Pseudanthias bicolor (Bicolor Anthias / Yellowback Basslet)
• Small fish safe: ✅ Yes
• Small invert safe: ✅ Yes
• Coral safe: ✅ Yes
• Minimum tank size: 265L+ (preferably larger for groups)
• Adult size: ~13 cm (5 inches)
• Diet: Carnivorous (zooplankton, frozen mysis/brine shrimp, enriched flake foods)
• Be aware of: Requires frequent feedings due to high metabolism. Best kept in harems (one male with multiple females). Sensitive to aggression from dominant tank mates.
Bicolor Anthias (Pseudanthias bicolor) – A Vibrant and Graceful Reef Fish
The Bicolor Anthias, also known as the Yellowback Basslet, is a strikingly colorful species found across Indo-Pacific coral reefs. It is a social, active, and visually stunning anthias, making it a favorite choice among reef aquarists. However, like many anthias, it requires frequent feeding and a well-structured environment to thrive in captivity.
Appearance and Coloration
The Bicolor Anthias is instantly recognizable due to its:
• Bright yellow dorsal region, running from head to tail.
• Lavender to pinkish-purple body, creating a striking two-tone effect.
• Long, flowing dorsal fin filaments in males, used for displays.
• Females appearing more pastel, with rounded fins and a subtler color gradient.
This unique combination of yellow and lavender tones makes Pseudanthias bicolor a distinct and eye-catching species.
Natural Habitat and Behaviour
Native to the Indo-Pacific, including Mauritius, Réunion, Indonesia, and northern Australia, Bicolor Anthias inhabit:
• Lagoon patch reefs and outer reef slopes, typically in strong current areas.
• Depths of 10-50 meters (30-165 feet), often hovering over coral structures.
• Large shoaling groups, where they form harems with one dominant male and multiple females.
• Active mid-water swimming behavior, feeding on passing zooplankton.
In captivity, they thrive in well-structured aquariums with open water areas and strong water flow to mimic their natural conditions.
Tank Requirements and Water Parameters
Due to their active nature, Bicolor Anthias require a well-structured, stable aquarium environment.
• Minimum tank size: 265L+ (70 gallons) for a small group; larger tanks (380L+) recommended for harems.
• Temperature: 22–25.5°C (72–78°F)
• pH: 8.1–8.4
• Salinity: 1.020–1.025
• Water movement: Moderate to strong, mimicking reef currents.
• Aquascaping: Provide ample live rock formations, with caves and ledges for security.
⚠ Ensure the aquarium has a secure lid, as Bicolor Anthias are known jumpers.
Diet and Feeding
Bicolor Anthias are planktivores, requiring frequent feedings throughout the day. Their ideal diet includes:
• Frozen mysis and brine shrimp – Essential protein sources.
• Enriched frozen plankton – Helps mimic their natural diet.
• High-quality marine pellets and flakes – Should be vitamin-enriched.
• Live foods (copepods, amphipods, rotifers) – Particularly beneficial for newly introduced fish.
Feeding frequency: At least 3 times per day to sustain energy levels and maintain vibrant coloration.
Compatibility and Tank Mates
Bicolor Anthias are peaceful fish, making them a great choice for community reef tanks.
✔ Compatible with:
• Other peaceful reef fish, such as Clownfish, Wrasses, Firefish, and Blennies.
• Small to medium-sized Tangs, which do not intimidate them.
• Reef-safe invertebrates, such as cleaner shrimp, snails, and crabs.
❌ Avoid housing with:
• Large, aggressive fish, such as Triggers, Groupers, or large Dottybacks.
• Fast-moving, competitive feeders, which may prevent them from eating.
• Overly dominant anthias species, which may create territorial disputes.
⚠ If keeping multiple Bicolor Anthias, introduce them as a group to establish a stable hierarchy.
Behavior and Social Structure
Unlike some anthias species, Bicolor Anthias:
• Are highly social, preferring to school rather than remain solitary.
• Establish harems, where the largest female may transition to male if the dominant male is lost.
• Are mid-water swimmers, rather than hiding in rock crevices.
Their energetic, shoaling behavior makes them a fantastic addition to well-stocked reef aquariums.
Health and Disease Considerations
Bicolor Anthias are somewhat delicate, and they can be susceptible to:
• Malnutrition, if not fed frequently enough.
• Marine Ich (Cryptocaryon irritans), particularly when stressed.
• Bacterial infections, often linked to shipping stress.
To keep them healthy:
✔ Feed multiple times per day to prevent starvation.
✔ Ensure strong water movement to provide oxygenation.
✔ Acclimate slowly, as they can be sensitive to sudden environmental changes.
Lifespan and Long-Term Care
With proper care, Bicolor Anthias can live up to 5-7 years in captivity. Their striking color contrast, peaceful nature, and shoaling behavior make them a rewarding addition to established reef aquariums.
Why Choose a Bicolor Anthias?
✔ One of the most uniquely colored anthias, with a blend of yellow and lavender hues.
✔ Highly social, adding movement and life to reef tanks.
✔ Reef-safe, with no risk to corals or invertebrates.
✔ Easy to pair with peaceful tank mates, making them ideal for community aquariums.
⚠ Important Considerations Before Buying a Bicolor Anthias:
🚫 Requires multiple daily feedings, making them unsuitable for low-maintenance tanks.
🚫 Sensitive to dominant tank mates, needing careful species selection.
🚫 Best kept in groups, requiring a spacious tank for proper social behavior.
🚫 Can be difficult to acclimate, requiring slow introduction and close monitoring.