FishMarineIntermediate
©AI Generated·Proprietary
Red-bar Anthias
Pseudanthias cooperi
A beautiful medium-sized Anthias from the Indo-Pacific, featuring a slender streamlined body and a distinct bright red stripe in males.
Water Temperature
22 - 27 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
All levels
Adult size
14 cm
Minimum tank volume
>= 300 L
Minimum group
>= 4
GH
15 - 25 dGH
KH
8 - 12 dKH
Species description
Geographical Origin and Habitat: Broadly distributed in the tropical Indo-Pacific, from the Red Sea and East Africa to the Line Islands, north to southern Japan, and south to Australia and New Caledonia. Inhabits current-swept reefs at depths of 10 to 60 meters.
Taxonomy and Morphology: Belonging to the family Serranidae. Features a slender, streamlined body typical of water column feeders. Reaches a maximum total length of approximately 14 cm.
Social Behavior: Forms large schooling harems composed of a single dominant male and a harem of females. They swim actively and tightly together to deter predators.
Coloration and Sexual Dimorphism: The male is reddish-pink with a distinctive vertical blood-red bar or patch in the middle of the flanks, and blue-tipped fins. The female is uniform pinkish-orange, lacking the red bar.
Care, breeding and tankmates
Aquarium Setup: Demands an aquarium of at least 300 liters to house a small group. Ample open swimming space and rock structures forming caves and tunnels are required. Excellent filtration with a strong skimmer is necessary. A lid is mandatory.
Diet and Feeding: Zooplanktivorous. In captivity, it must be fed 2 to 3 times daily with frozen foods like mysis, brine shrimp, and calanus. It can eventually adapt to high-quality dry micro-granules.
Water Quality: Pristine and highly oxygenated water is required. Temperature 22-27°C, pH 8.1-8.4, salinity SG 1.020-1.026. GH 15-25. Needs strong water movement to mimic its native current-swept habitat.
Compatibility and Cohabitation: 100% reef safe. Ideal for SPS and LPS reef aquariums. Coexists peacefully with other docile reef fish. Do not house with highly aggressive species or large predators.
Aquarium Breeding: Protogynous hermaphrodite. Captive reproduction is undocumented due to the extreme difficulty of raising pelagic larvae.
Risks and Diseases: Highly prone to starvation if not fed multiple times a day. Susceptible to marine ich (Cryptocaryon) if subjected to rapid temperature changes.
Geographic Origin and Distribution
Broadly distributed in the tropical Indo-Pacific, from the Red Sea and East Africa to the Line Islands, north to southern Japan, and south to Australia and New Caledonia. Inhabits current-swept reefs at depths of 10 to 60 meters.
Origin
Tropical oceans and reefsAfrica and MadagascarEast AsiaAustralia, New Guinea, and Oceania
Fish profile
- Temperament
- Peaceful
- The temperament of Pseudanthias cooperi is generally peaceful towards completely unrelated fish, making them wonderful community residents. However, they establish a strict pecking order within their own group, which can involve some chasing and posturing. The dominant male will frequently display to the females to maintain his status and keep the harem in line. While usually harmless, this internal squabbling requires adequate space and hiding spots for subordinate individuals. They should not be housed with overly aggressive predators that might bully or consume them.
- Diet
- Carnivore
- In the wild, Pseudanthias cooperi is a dedicated zooplanktivore that constantly picks tiny organisms from the water column. In the home aquarium, they require a varied diet consisting of high-quality frozen or live meaty foods. Suitable options include mysis shrimp, enriched brine shrimp, copepods, and finely chopped seafood. Getting them to accept dry prepared foods like high-quality flakes or small pellets can take time and patience. A diverse nutritional profile is crucial for maintaining their vibrant coloration and immune health.
- Life expectancy
- 5-7 years
- The Red-bar Anthias has a life expectancy in the aquarium of typically around 5 to 7 years when housed under optimal conditions. To achieve this longevity, it is essential to ensure stable water quality free from chemical fluctuations. Proper nutrition based on small, frequent meals is the key to preventing premature wasting due to its fast metabolism. Stress caused by overly aggressive tank mates can significantly reduce its lifespan.
- Adult size
- 14 cm
- The catalog's scalar value is 14 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 14 cm for this species, recorded as total length (TL). The taxonomic record consulted is Pseudanthias cooperi (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Harem
- This species exhibits a fascinating social structure characterized by protogynous hermaphroditism, where all individuals are born female. A typical group consists of a single dominant male maintaining a harem of several females. If the dominant male is removed or dies, the largest and most dominant female will morph into a male to take his place. For the home aquarium, it is best to purchase a group of females and allow this natural transition to occur. Keeping multiple males usually results in fatal aggression unless the tank is massive.
- Feeding frequency
- 2-3 times daily
- Due to their incredibly active metabolism and natural grazing behavior, Pseudanthias cooperi requires multiple feedings throughout the day. It is highly recommended to feed them small amounts at least three to four times daily. Infrequent, large feedings are poorly digested and can lead to malnutrition or starvation over time. Automated feeders can be very useful for dispensing small amounts of dry food while the aquarist is away. Consistent, frequent meals are the key to long-term success with this species.
- Bioload
- Medium
- Pseudanthias cooperi contributes a moderate amount to the overall bioload of a marine aquarium system. Due to their highly active nature and constant swimming, they require frequent feedings which indirectly increases the organic waste produced. Excellent filtration and regular water changes are strongly recommended to process these nutrients. Maintaining a robust protein skimmer will help manage the dissolved organics effectively. Proper husbandry ensures that the bioload remains manageable over the long term.
- Flow
- Strong
- This species originates from dynamic reef environments where strong water movement is a constant factor. Pseudanthias cooperi thrives in aquariums that provide moderate to strong, turbulent water flow across the aquascape. Brisk currents simulate their natural habitat and encourage their natural schooling and feeding behaviors in the water column. Powerheads or wavemakers should be positioned to create broad, sweeping flow patterns rather than harsh, direct streams. Adequate flow also keeps particulate food suspended longer, giving them more time to feed.
- Jump risk
- Yes
- Like many highly active reef fishes, Pseudanthias cooperi presents a moderate to high risk of jumping out of an open aquarium. They are easily startled by sudden movements, lighting changes, or aggressive tank mates, which can trigger a flight response. It is strongly advised to keep a tight-fitting lid or a custom mesh screen over the tank at all times. Even small gaps around equipment and overflow boxes should be covered to prevent tragic accidents. Taking these precautions is a simple but vital part of their husbandry.
- Reproduction
- Protogynous hermaphrodite
- Breeding Pseudanthias cooperi in a home aquarium is exceptionally rare and presents significant challenges for even advanced hobbyists. They are pelagic spawners that release their eggs and sperm into the water column during synchronized mating rituals. The resulting larvae are microscopic and require highly specialized, perfectly sized live planktonic foods to survive. Furthermore, the larval stage is extremely long and sensitive to minute changes in water quality. Consequently, nearly all specimens available in the trade are wild-caught rather than captive-bred.
- Compatibility & tankmates
- Peaceful
- This species is generally considered completely reef safe and makes a stunning addition to mixed reef aquariums. Pseudanthias cooperi will typically ignore corals, sessile invertebrates, and most motile invertebrates like ornamental shrimp. They are generally peaceful towards heterospecifics but can display significant aggression towards other Anthias species. It is usually best to keep them as the only Anthias species in the tank unless the aquarium is exceptionally large. Careful observation is needed when introducing new tank mates to ensure harmony.
- Tank level
- All levels
- Throughout the day, Pseudanthias cooperi will predominantly occupy the middle to upper levels of the water column. They are highly visible fish that love to hover above the reef structure, facing into the current to catch passing food. At night or when frightened, they will quickly dart into the rockwork to seek shelter in crevices and caves. Providing plenty of open swimming space alongside complex rock formations is essential for their comfort. Their active presence brings a wonderful sense of movement and life to the upper reef zones.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.4 ± 0.45 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01047, b = 2.94
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
