Description

The Threadfin Anthias most commonly refers to Pseudanthias huchtii (also known as the Red Cheek Fairy Basslet or Pacific Basslet). There's also Nemanthias carberryi, sometimes called the Threadfin Anthias or Carberryi Anthias, which has similar care but is from the Indian Ocean. For the purpose of this guide, we'll focus on Pseudanthias huchtii due to its commonality and distinctive "threadfin" appearance, but much of the general anthias care applies to both.

Anthias are known for their vibrant colours, active swimming, and schooling behaviour, making them highly desirable for reef aquariums. However, their high metabolic rate and feeding requirements can make them challenging for beginners.

Appearance:

Males: More vibrantly coloured. They typically have a yellowish to orange-pink body, often with a distinctive red or reddish-orange patch/stripe on the cheek (hence "Red Cheek Fairy Basslet"). The dorsal and anal fins can have blue or purple margins. Males also develop extended, flowing filaments or "threads" on their dorsal fin, which is where the common name "Threadfin" comes from.
Females: Generally paler, more of a pinkish-orange or light yellow body, lacking the prominent red cheek patch and the extended dorsal fin filaments.
Sexual Dimorphism and Hermaphroditism: Like all Pseudanthias species, they are protogynous hermaphrodites. All individuals are born female, and the largest and most dominant female will change sex to become a male. Males are territorial and guard a harem of females.

Adult Size:

Threadfin Anthias typically reach an adult size of 4 to 5 inches (10-12 cm) in captivity.

Natural Habitat and Distribution:

Found in the Western Central Pacific Ocean, from the Maluku Islands and the Philippines east to Vanuatu, and south to the Great Barrier Reef in the Tasman Sea, as well as Scott Reef and Ashmore Reefs in the Timor Sea. Their distribution also extends as far east as Palau in Micronesia. This means they are found in waters relevant to Caboolture, Queensland.
Inhabit aggregations at drop-offs and outer crests of coral reefs, usually at depths of 4-30 meters (typically 10-30 meters). They feed on zooplankton in the water column.

Aquarium Care (Intermediate to Advanced Level):

Minimum Tank Size: Due to their active swimming and schooling nature, a minimum of 75 gallons (approximately 284 liters) is recommended for a small group (3-5 individuals). For larger harems or multiple species of anthias, 100-150 gallons or more is highly preferred to provide ample space and reduce aggression. Longer tanks are better than taller ones to allow for more horizontal swimming.
Water Parameters: Maintaining pristine and highly stable reef tank conditions is paramount. Anthias are very sensitive to fluctuations.
- Temperature: 74-78°F (23-26°C)
- Salinity: 1.023-1.025 specific gravity
- pH: 8.1-8.4
- Alkalinity (dKH): 8-12 dKH
- Ammonia and nitrites must be 0 ppm. Nitrates should be kept as low as possible, ideally under 10 ppm.
Filtration: A robust and efficient filtration system, including a strong protein skimmer, is essential to handle their bio-load and maintain water quality. Anthias are active and require highly oxygenated water.
Water Flow: They require strong, turbulent water flow (random and varied) to mimic their natural reef environment where they feed in currents. Powerheads and wavemakers are crucial.
Diet:
- Planktivorous Carnivores: In the wild, they feed constantly on zooplankton in the water column. This translates to a very high metabolic rate and a need for frequent, small feedings in the aquarium. This is often the biggest challenge for long-term success.
- Feeding Frequency: A minimum of 3-4 times daily is recommended, and some aquarists feed them even more often (5-6 times). Consider an automatic feeder for dry foods.
- Recommended Foods:
  - Frozen Mysis Shrimp: A staple and highly accepted food.
  - Enriched Brine Shrimp: Also readily accepted.
  - Copepods and Amphipods: Live copepods (from a refugium or cultured) are an excellent supplement.
  - High-quality marine pellets and flakes: Especially small sizes, often enriched with Spirulina or garlic. Many anthias learn to accept dry foods, which is essential for frequent feeding.
  - Finely chopped seafood like krill or clam.
Temperament:
- Peaceful (towards other species): Generally peaceful towards most other reef-safe tank mates. They are active and can help draw out shyer fish.
- Social Structure (within group): Best kept in groups with a single male and multiple females (a harem). A ratio of 1 male to 3-5+ females is ideal. If you introduce a group of juveniles, the largest will eventually become the male. If the male dies, the most dominant female will change sex.
- Intraspecific Aggression: While generally peaceful, males can be territorial, especially towards other males or newly introduced anthias. Ensure adequate space and hiding spots.
Reef Compatibility: Excellent reef compatibility. Anthias are considered truly reef safe. They will not harm corals, clams, or most invertebrates, making them ideal for mixed reef aquariums. They occupy the mid-water column, adding movement and color without disturbing the substrate or corals.
Tank Setup:
- Provide plenty of live rock with caves, crevices, and overhangs for hiding and resting, especially during the night or when stressed.
- Ensure ample open swimming space in the water column for their schooling behavior.
- A tight-fitting lid is absolutely essential as Anthias are notorious jumpers, especially when startled or new to the tank.
Disease Susceptibility: Anthias can be susceptible to marine ich (Cryptocaryon irritans) and other parasitic infections if stressed, underfed, or in poor water quality. They are also prone to Uronema infections. Maintaining pristine conditions and a consistent, nutritious diet is key to their health.
Acclimation: Slow and careful drip acclimation is crucial due to their sensitivity during transport and to parameter changes.
Quarantine: Highly recommended to quarantine new arrivals for several weeks to observe for health issues, ensure they are eating well, and allow them to de-stress before introduction to the main display.

The Threadfin Anthias is a stunning and captivating addition to a well-maintained, mature reef aquarium. Their vibrant colors and schooling behavior can add dynamic beauty to a tank, but their high feeding demands mean they are best suited for intermediate to advanced aquarists who can meet their specific needs.

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