TankBud

Square anthias

Pseudanthias pleurotaenia

Also known as Pink Square Anthias, Squareback Anthias, Squarespot Anthias, Purple Blotch Basslet

SaltwaterFish

Square anthias (Pseudanthias pleurotaenia)
Jenny (JennyHuang) from Taipei · CC BY 2.0

Care at a glance

Temperature
72–79°F
22–26°C
pH
8.1–8.4
Adult size
7.9 in
20 cm
Minimum tank
100 gal
380 L
Temperament
Mostly peaceful
Social behavior
Social
Swim level
Middle
Difficulty
Medium
Breeding
Hard
Rarity
Common
Reef safe
Reef safe
Family
Serranidae
Origin
Western Pacific and eastern Indian Ocean reefs, from Indonesia to Samoa, north to the Ryukyu Islands, south to New Caledonia

Overview

Timid and easily stressed when new, slower to start feeding than other anthias, and best added to a tank with existing anthias or other peaceful fish already settled in. It needs several feedings of small meaty foods a day and does poorly on one or two large meals. Males fight other males of the species to the death, so keep only one per tank, ideally with four to six females; females also peck at smaller conspecifics, so add similarly sized individuals together. It is fully reef safe with corals and invertebrates but should be kept away from aggressive tankmates, large angelfish, and predatory fish that could bully or eat it.

In the wild

Ranges across the western Pacific and into the eastern Indian Ocean on outer reef slopes and drop-offs, from the shallows down past 100 m though most common in the top 25 m. It needs a large aquarium with a long, open swimming lane above a substantial rock structure, since males patrol and defend a real territory. Keep lighting on the lower, indirect side, since harsh light washes out its color and adds stress.

Good to know

A protogynous hermaphrodite and harem former: females hold their own pecking order within a group, and the largest female steps up to replace a lost male. It shows strong sexual dimorphism: females are yellow-orange with a lavender belly, while males turn a deep pink to reddish-purple with a squared-off patch of color on the flank that gives the species its common name. It is one of the largest anthias kept in the hobby.

Did you know

The dominant male's square block of purple-pink color is a signal of status that subordinate males and females never show, so the presence of a fully colored square patch is a reliable sign of which fish is running the harem.

Weekly picks

Tank mates

Square anthias is a mostly peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a Square anthias need?

A Square anthias needs at least 100 gal (380 L). It spends most of its time in the middle.

What temperature and pH does a Square anthias need?

A Square anthias is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.

How big does a Square anthias get?

An adult Square anthias reaches about 7.9 in (20 cm).

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