Pink Square Anthias (Pseudanthias Pleurotaenia) saltwater aquarium fish

Overview:

Pink Square Anthias are delicate, active marine reef fish best kept in a mature, stable saltwater aquarium. They do best in a large, peaceful system with plenty of open swimming space, along with rockwork that offers caves and ledges for shelter. Because they are plankton-feeders by nature, strong but non-bulky flow and excellent oxygenation are important. A sand bed is not required, but stable water quality is. Ideal conditions include pristine water, low nitrate and phosphate, consistent salinity, and warm tropical temperatures. This species is sensitive to sudden changes, so gradual acclimation and steady maintenance are essential. They thrive in groups when space allows, and males may display brighter coloration and more assertive behavior.

Diet and Feeding:

Pink Square Anthias need frequent, small meals throughout the day. In the wild they feed continuously on tiny zooplankton, so one large feeding is not enough. Offer a varied diet of enriched frozen mysis, copepods, enriched brine shrimp, finely chopped seafood, and high-quality marine pellets designed for planktivores. Feeding 2–4 times daily is ideal, and automatic feeders can help maintain consistency. Soaking foods in vitamin supplements and marine fatty acids supports long-term color, energy, and immune health. They often lose condition if underfed, so watch body shape closely; a sunken belly is a warning sign. In mixed reef systems, target feeding may be necessary to ensure they receive enough food before faster tankmates consume it.

Compatibility:

Pink Square Anthias are generally peaceful and are best paired with other calm reef-safe fish. Suitable tankmates include gobies, blennies, cardinals, clownfish, and smaller wrasses that are not overly aggressive. Avoid boisterous, territorial, or competitive species such as large tangs, triggers, dottybacks, and aggressive wrasses, as these can outcompete or stress them. They should not be housed with predators large enough to view them as prey. If keeping multiple anthias, introduce them together and provide ample space and hiding areas to reduce hierarchy stress. In smaller tanks, one individual or a bonded pair may be easier to maintain than a group. Their peaceful nature makes them excellent reef residents, but they can become timid if bullied or if feeding competition is too intense.

Health and Quarantine:

This species is prone to stress-related issues if water quality slips or feeding is inconsistent. Common concerns include weight loss, bacterial infections, and parasite outbreaks such as marine ich or velvet. A careful quarantine period of 4–6 weeks is strongly recommended before adding them to the display. During quarantine, observe eating behavior, treat parasites if needed, and ensure the fish is steadily gaining weight. Because anthias are sensitive, all medication should be used cautiously and only when appropriate. Preventive care includes stable parameters, varied nutrition, frequent feeding, and avoiding abrupt changes in temperature or salinity. Healthy Pink Square Anthias are active, alert, and full-bodied; lethargy, faded color, or refusal to eat should be addressed immediately.

mysis shrimp brine shrimp finely chopped meaty foods
Pink Square Anthias are highly active, midwater planktivores that spend most of their time in constant, open-water cruising and darting through the water column, so they require ample swimming space with secure hiding areas and plenty of structure. They are generally peaceful toward noncompetitive tank mates but can be mildly hierarchical and territorial with conspecifics, especially in smaller groups or cramped quarters. A minimum tank size of 75 gallons is recommended for a small group, with a larger system preferred to maintain stable social spacing and reduce stress. An aquascape built with branching rockwork and visual barriers helps break lines of sight, giving subordinate fish respite and encouraging more natural behavior. They are typically compatible with other reef-safe species, provided tank mates are not overly aggressive or fast enough to outcompete them for food. Their diet is omnivorous with a strong emphasis on zooplankton, and in captivity they do best on frequent offerings of small meaty foods such as mysis, enriched brine shrimp, copepods, and finely chopped marine preparations that match their natural hunting style.

FAQ

Frequently Asked Questions

About the Pink Square Anthias

  • Is Pink Square Anthias best kept as a single fish, or does it need a group?
    It is much better kept in a small harem or group, not alone. Like most anthias, the most stable setup is one dominant male with 3–6 females. A lone Pink Square Anthias often becomes timid, refuses food, or fades in color. If kept in a pair, make sure one is clearly male and the other is female; two similar-sized individuals may fight.
  • What foods reliably get Pink Square Anthias feeding in captivity?
    They usually do best on frequent small feedings of meaty planktonic foods: enriched mysis, copepods, baby brine shrimp, finely chopped krill, and high-quality marine pellets designed for planktivores. The key is variety and frequency. Offer food 2–4 times daily if possible. Newly imported fish often start with live or frozen copepods and baby brine shrimp before accepting pellets.
  • How can I tell if a Pink Square Anthias is male or female?
    Males are typically more intensely colored, more assertive, and often show more elongated dorsal, anal, or caudal fin extensions depending on the individual. Females are usually smaller, rounder in profile, and less vivid. In a group, the largest, most dominant individual often transitions into male if no male is present.
  • What tank setup suits Pink Square Anthias best long-term?
    They do best in a mature reef-style aquarium with strong water movement, high oxygenation, and plenty of open swimming space plus some sheltered rockwork. Stability matters more than minimalism: low nitrate, no sudden salinity swings, and excellent filtration are important because they are sensitive to poor water quality. A tight-fitting lid is also important, since anthias are jumpers.
  • Why do Pink Square Anthias sometimes waste away even when they seem to be eating?
    This is a common anthias problem and usually comes from not feeding often enough, foods being too large or too rich, or the fish being outcompeted at meals. They burn energy quickly and need frequent access to small, nutrient-dense foods. Another issue is internal parasites or shipping stress, especially in newly imported specimens. If one is eating less, isolate it if needed, increase feed frequency, and watch closely for rapid weight loss behind the head and belly.