Pseudanthias evansi (Yellowback Anthias / Evansi Anthias)
• Small fish safe: ✅ Yes
• Small invert safe: ✅ Yes
• Coral safe: ✅ Yes
• Minimum tank size: 400L+ (preferably larger for groups)
• Adult size: ~12 cm (4.7 inches)
• Diet: Carnivorous (zooplankton, frozen mysis/brine shrimp, enriched flake foods)
• Be aware of: Needs frequent feedings due to high metabolism. Best kept in harems (one male with multiple females). Timid nature—may be outcompeted for food. Prone to stress during acclimatization.
Yellowback Anthias (Pseudanthias evansi) – A Delicate but Beautiful Reef Fish
The Yellowback Anthias, also known as Evansi Anthias or Yellowtail Goldie, is a graceful and brightly colored schooling species found in the Indian Ocean. This anthias is known for its stunning yellow and violet hues and fast-moving, shoaling behavior. While beautiful, it is one of the more delicate anthias species, requiring expert care and frequent feeding to thrive in captivity.
Appearance and Coloration
The Yellowback Anthias is instantly recognizable due to its:
• Vibrant violet to pinkish-purple body, with an iridescent sheen.
• Bright yellow dorsal region, extending from the head to the tail.
• Long, slender body shape, built for constant swimming.
• Subtle sexual dimorphism, with males slightly larger and more vibrant.
This soft gradient of colors makes Pseudanthias evansi one of the most visually striking anthias species available.
Natural Habitat and Behaviour
Native to the Indian Ocean, including Sri Lanka, the Maldives, and Mauritius, Yellowback Anthias inhabit:
• Deep reef slopes and outer reef walls, usually at depths of 4 to 40 meters (13 to 130 feet).
• Large, fast-moving schools, often numbering in the hundreds.
• Haremic social structures, consisting of one dominant male and multiple females.
• Non-territorial nature, preferring open-water swimming over reef hiding.
In captivity, they thrive in well-structured aquariums with open swimming space and moderate water flow.
Tank Requirements and Water Parameters
Due to their active schooling nature, Yellowback Anthias require a spacious tank with excellent water quality.
• Minimum tank size: 400L+ (106 gallons) for a small group; larger tanks (500L+) recommended for harems.
• Temperature: 24–28°C (75–82°F)
• pH: 8.1–8.4
• Salinity: 1.020–1.025
• Water movement: Moderate to strong, simulating natural reef currents.
• Aquascaping: Provide open water swimming areas with live rock structures for occasional retreat.
⚠ Ensure the aquarium has a secure lid, as Yellowback Anthias are prone to jumping when startled.
Diet and Feeding
Yellowback Anthias are planktivores, requiring frequent feedings throughout the day to maintain health and energy levels. Their ideal diet includes:
• Frozen mysis and brine shrimp – Essential protein sources.
• Enriched frozen plankton – Mimics natural diet and enhances coloration.
• High-quality marine pellets and flakes – Must be nutrient-rich and small-sized.
• Live foods (copepods, amphipods, rotifers) – Particularly beneficial during acclimation.
Feeding frequency: At least 4 times per day to prevent starvation and maintain coloration.
Compatibility and Tank Mates
Yellowback Anthias are peaceful fish, making them a great choice for community reef tanks.
✔ Compatible with:
• Other peaceful, reef-safe fish, such as Firefish, Gobies, and Fairy Wrasses.
• Small to medium-sized Tangs, which provide movement without aggression.
• 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 cause stress or hierarchy conflicts.
⚠ If keeping multiple Yellowback Anthias, introduce them as a group to prevent aggression.
Behavior and Social Structure
Unlike some anthias, Yellowback Anthias:
• Are shy and delicate, requiring low-stress tank environments.
• Prefer schooling in groups, rather than establishing territories.
• Exhibit natural dominance hierarchies, where the largest female may transition to male if the dominant male is lost.
Their gentle nature and shoaling behavior make them a dynamic addition to larger reef tanks.
Health and Disease Considerations
Yellowback Anthias are highly sensitive, and they can be vulnerable to:
• Malnutrition, if not fed frequently enough.
• Marine Ich (Cryptocaryon irritans), particularly if stressed.
• Bacterial infections, usually due to poor water conditions.
To keep them healthy:
✔ Feed multiple times per day to prevent malnutrition.
✔ Ensure high water quality with strong filtration.
✔ Acclimate slowly, as they are easily stressed during transport.
Lifespan and Long-Term Care
With proper care, Yellowback Anthias can live up to 5 years in captivity. Their stunning coloration, peaceful nature, and schooling behavior make them a great choice for experienced aquarists.
Why Choose a Yellowback Anthias?
✔ Visually stunning, with vibrant purple and yellow hues.
✔ Active and social, adding movement and life to reef tanks.
✔ Reef-safe, with no risk to corals or invertebrates.
✔ Fascinating schooling behavior, making them enjoyable to observe.
⚠ Important Considerations Before Buying a Yellowback Anthias:
🚫 Requires frequent feedings, making them unsuitable for low-maintenance tanks.
🚫 Sensitive to aggressive tank mates, needing peaceful companions.
🚫 Best kept in large groups, which means a spacious tank is necessary.
🚫 Can be difficult to acclimate, requiring slow introduction and careful monitoring.