Common name: Squareback Anthias

Care

Squareback Anthias require a well-maintained aquarium with plenty of swimming space and hiding spots. A tank of at least 300 liters (80 gallons) is recommended for a small group, with larger tanks being preferable for larger schools. Live rock structures with overhangs and caves provide essential shelter and help reduce stress.

These fish prefer stable water conditions with moderate to strong water flow to mimic their natural reef habitat. They are sensitive to poor water quality, so regular maintenance and efficient filtration are crucial. Lighting should be moderate to bright, as it helps showcase their vibrant colors.

Squareback Anthias are best kept in groups with a single dominant male and several females. This setup mimics their natural harem structure and helps reduce aggression. Avoid housing them with overly aggressive tank mates, as this can lead to stress and health issues.

Diet and Feeding

In the wild, Squareback Anthias are planktivores, feeding on zooplankton carried by ocean currents. In captivity, they require a varied diet that includes high-quality frozen or live foods such as mysis shrimp, brine shrimp, and copepods. Supplement their diet with enriched flakes or pellets formulated for carnivorous marine fish.

Feed them small portions multiple times a day to mimic their natural feeding behavior. Anthias have high metabolisms and benefit from frequent, smaller feedings rather than a single large meal. This feeding schedule also helps maintain their vibrant coloration and overall health.

Behavior and Compatibility

Squareback Anthias are generally peaceful but can exhibit territorial behavior, especially among males. It is essential to maintain a proper male-to-female ratio (typically one male to several females) to minimize aggression. In larger tanks, multiple harems can coexist if sufficient space and hiding spots are provided.

They are excellent additions to reef tanks and are considered reef-safe, as they do not harm corals or invertebrates. Compatible tank mates include other peaceful or semi-aggressive species such as tangs, wrasses, and gobies. Avoid housing them with overly aggressive fish that may outcompete them for food or intimidate them.

Reproduction

Squareback Anthias are protogynous hermaphrodites, meaning all individuals are born female, and the dominant individual in a group transitions to male. This fascinating reproductive strategy ensures that a harem always has a breeding male. In captivity, breeding is rare but possible under optimal conditions, including stable water parameters and a stress-free environment.

The female lays eggs in the water column, which are fertilized by the male. The eggs hatch into planktonic larvae, which are challenging to rear due to their small size and specific dietary needs. Breeding efforts are typically undertaken by advanced aquarists or in specialized facilities.

Health and Common Issues

Squareback Anthias are relatively hardy but can be prone to stress-related illnesses if kept in suboptimal conditions. Common health issues include marine ich and bacterial infections, often triggered by poor water quality or inadequate diet. Quarantining new additions and maintaining pristine water conditions are essential preventive measures.

When selecting a Squareback Anthias, look for active individuals with bright colors and no visible signs of disease. Avoid fish that appear lethargic, have clamped fins, or show signs of rapid breathing.

Habitat

In the wild, Squareback Anthias inhabit the outer reef slopes and drop-offs of the Indo-Pacific region. They are typically found at depths ranging from 10 to 50 meters (35 to 165 feet), where they form large schools and feed on plankton carried by currents. Their natural habitat is characterized by clear, warm waters with strong currents and abundant coral structures.

To replicate their natural environment in captivity, provide a spacious tank with plenty of open swimming areas and live rock structures for shelter. Moderate to strong water flow is essential to mimic the currents of their native habitat.