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Cocos Girdled Wrasse

Halichoeres discolor

Endemic to Cocos Island, this active and streamlined wrasse features a vivid yellowish-brown coloration. A deep sand bed is absolutely essential for its natural sleeping habits.

Taxonomy
Class:Actinopteri
Order:Perciformes
Family:Labridae
Genus:Halichoeres
Species:Halichoeres discolor

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Water Temperature

23 - 28 °C

pH Value

8.1 - 8.4

Water type

Marine

Tank level

Bottom and middle

Adult size

11 cm

Minimum tank volume

>= 200 L

Minimum group

>= 1

Species description

Geographical Origin and Habitat: This marine fish is endemic to the coastal waters of Cocos Island (Costa Rica) in the Eastern Pacific. It is found around rocky reefs, boulders, and sandy patches at depths ranging from 3 to 15 meters.
Taxonomy and Morphology: Belonging to the family Labridae and the genus Halichoeres. Features a slender, streamlined, and slightly compressed body with a terminal mouth. It grows to an adult length of 10 to 15 centimeters.
Social Behavior: Highly active and diurnal. It spends the day actively swimming and scanning the sand and rocks for food. Like most wrasses, it burrows into the sand at night to sleep or seek protection.
Coloration and Sexual Dimorphism: Exhibits a variable yellowish-brown base color with lighter vertical bands or girdles along the flanks. Males in the terminal phase display more vivid colors and longer fin filaments than females.

Care, breeding and tankmates

Aquarium Setup: An aquarium of at least 250 liters is recommended. A deep sand bed of 5-7 cm using fine, smooth sand is absolutely mandatory to allow natural sand-burying behavior. Provide plenty of live rock caves.
Diet and Feeding: Carnivorous. Feed a variety of high-quality frozen foods, including mysis shrimp, brine shrimp, chopped krill, clams, and squid. It will also accept premium marine dry pellets over time.
Water Quality: Maintain stable marine reef water parameters: temperature of 22.0 to 26.0 °C, pH range of 8.1 to 8.4, and salinity between 1.020 and 1.025. Ensure efficient protein skimming and moderate water flow.
Compatibility and Cohabitation: Peaceful toward most non-wrasse tankmates. However, it will actively consume small ornamental shrimps, tiny crabs, and flatworms, making it caution-safe for reef aquariums.
Aquarium Breeding: Spawning in captivity is not documented. Replicating the pelagic larval phase of this island-endemic species in a closed home aquarium is currently unfeasible.
Risks and Diseases: Jumps easily when frightened or during tank cleaning; a secure lid is essential. Lack of appropriate sand for burying leads to stress, skin abrasions, and susceptibility to marine Ich.

Geographic Origin and Distribution

This marine fish is endemic to the coastal waters of Cocos Island (Costa Rica) in the Eastern Pacific. It is found around rocky reefs, boulders, and sandy patches at depths ranging from 3 to 15 meters.

Origin

Tropical oceans and reefsCentral America and CaribbeanSouth and Southeast Asia

Fish profile

Temperament
Territorial
These wrasses are inquisitive, active, and generally peaceful community fish, although they can sometimes exhibit a semi-aggressive streak. They are constantly on the move, investigating crevices in the live rock for tiny morsels of food. While they do not usually bother corals directly, their constant picking behavior might accidentally irritate some sensitive polyps. Overall, they make a lively and entertaining addition to a moderately aggressive marine community tank.
Diet
Carnivore
This species is strictly carnivorous in its dietary habits. Their diet should consist of a variety of meaty foods including frozen mysis shrimp, vitamin-enriched brine shrimp, and high-quality marine flakes or pellets. In the wild, they naturally prey on small benthic invertebrates found among the rocks. Offering multiple small meals a day helps mimic their natural foraging behavior.
Sex ratio
Solitary
Many species within this genus are protogynous hermaphrodites, meaning dominant females can transition into males if needed. It is usually best to keep them singly or as a single male with multiple females if the tank is exceptionally large. Keeping two males in the same tank will almost certainly result in constant territorial disputes and fighting. Observing their intricate social structure and potential color changes during transition is fascinating.
Feeding frequency
Twice daily
Due to their highly active nature and high metabolisms, they require frequent feedings throughout the day. It is highly recommended to feed them at least two to three times daily. Providing smaller, more frequent meals is much better than offering one large meal. This feeding schedule ensures they maintain a healthy body weight and vibrant coloration.
Bioload
The bioload produced by this fish is considered moderate. They are very active swimmers and consume a significant amount of food, producing a fair amount of waste in return. Regular water changes and strong biological filtration are necessary to maintain pristine water quality. Protein skimmers are highly recommended for marine setups housing these energetic wrasses.
Flow
Strong
These fish thrive in aquariums with moderate to strong water flow throughout the tank. Good circulation closely mimics their natural reef environments and keeps them active and healthy. Powerheads should be strategically placed to create varied flow patterns mimicking ocean currents. However, ensure there are still some lower flow resting areas within the rockwork for them to retreat to.
Jump risk
Yes
Wrasses in this genus are notorious jumpers, especially when startled, chased, or newly introduced to an aquarium. A tight-fitting lid or a fine mesh screen is absolutely mandatory to keep them safe. Many aquarists have unfortunately lost these beautiful fish due to open-top tanks or small gaps in the canopy. The jump risk remains exceptionally high throughout their entire lifespan in captivity.
Reproduction
Not bred in captivity
Breeding these wrasses in a home aquarium is extremely rare and very difficult to achieve. They are pelagic spawners, naturally releasing their eggs and sperm directly into the water column. The resulting larvae require specialized microscopic foods and undergo a long, vulnerable planktonic stage. Therefore, almost all specimens available in the aquarium trade are wild-caught rather than captive-bred.
Compatibility & tankmates
With caution
The Halichoeres discolor wrasses are generally peaceful but can be aggressive towards smaller invertebrates like ornamental shrimp and feather dusters. They are considered reef safe with caution, as they will hunt for small prey. They usually coexist well with other similarly sized, semi-aggressive fish but might bully much smaller, more docile species. It is crucial not to keep them with large, aggressive predators that might see them as a snack.
Tank level
Middle/Bottom
They are highly active fish that will enthusiastically utilize all levels of the aquarium. However, they spend a significant amount of time hovering near the rockwork and sandy substrate actively looking for food. They require a deep sand bed of at least two to three inches to bury themselves in at night or when frightened. During the daytime, they will constantly patrol the middle and bottom sections of the tank.

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level
3.4 ± 0.5 se
Resilience
High (less than 15 months)
Phylogenetic uniqueness (PD50)
0.5
Bayesian Length-Weight
a = 0.01, b = 3.09
VulnerabilityLow vulnerability (10 / 100)

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

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Last updated: 06/30/2026
Cocos Girdled Wrasse (Halichoeres discolor) Care Guide & Tank Setup | Atlarium