Divided Wrasse
Halichoeres dimidiatus
The Divided Wrasse is a striking two-tone Brazilian reef fish, prized for its natural pest control. It requires a deep, soft sand bed for resting and a tightly covered aquarium.
Water Temperature
22 - 26 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
Bottom and middle
Adult size
12 cm
Minimum tank volume
>= 150 L
Minimum group
>= 1
Species description
Geographical Origin and Habitat: Southwestern Atlantic: endemic to the coast of Brazil and its oceanic islands (e.g., Fernando de Noronha). It inhabits shallow coral reefs, rocky shores, and adjacent fine sand beds down to a depth of 30 meters.
Taxonomy and Morphology: A member of the family Labridae, genus Halichoeres. It features a slender, elongated, torpedo-shaped body with a pointed snout and specialized teeth for preying on benthic micro-invertebrates. Grows to a maximum length of 12.0 cm.
Social Behavior: Diurnal, highly active, and inquisitive swimmer. It spends the day constantly inspecting rocks and substrate for food. When darkness falls or when threatened, it burrows headfirst into the sand bed to sleep.
Coloration and Sexual Dimorphism: Named for its distinct two-tone horizontal division: the upper half of the body is olive-green to yellow, while the lower half is silvery-white. Adult terminal males exhibit more vibrant markings with blue and pink highlights near the head.
Care, breeding and tankmates
Aquarium Setup: Requires an aquarium of at least 150 liters (approx. 40 gallons). It is critical to provide a deep bed of fine sand (5-8 cm / 2-3 inches) for burrowing. Coarse substrates will damage the fish. A tight lid or screen canopy is mandatory to prevent jumps.
Diet and Feeding: Active carnivore. Diet should consist of frozen foods such as mysis, brine shrimp, finely chopped seafood, and high-quality protein-rich dry pellets. Feed multiple small meals daily to keep up with its active metabolism.
Water Quality: Maintain stable marine conditions: temperature 22-26°C (72-78°F), pH 8.1-8.4, and specific gravity 1.020-1.025. Good filtration and carbon treatment are recommended to keep the water clear and free of organic build-ups.
Compatibility and Cohabitation: Reef-safe with corals, but will eat small ornamental shrimps, feather dusters, and tiny snails. It is an excellent utility fish, often introduced to control flatworms, pyramidellid snails, and other coral pests.
Aquarium Breeding: Protogynous hermaphrodite. It is a broadcast spawner, releasing buoyant pelagic eggs into the water column. There are no successful breeding reports in home aquariums due to the difficulty of rearing pelagic larvae.
Risks and Diseases: Subject to physical injury (abrasions, bacterial infections) if the sand substrate is too coarse or sharp. Jump risk is extremely high, especially during the first few days of introduction while acclimating.
Geographic Origin and Distribution
Southwestern Atlantic: endemic to the coast of Brazil and its oceanic islands (e.g., Fernando de Noronha). It inhabits shallow coral reefs, rocky shores, and adjacent fine sand beds down to a depth of 30 meters.
Origin
Tropical oceans and reefsExtra-Amazon South America
Fish profile
- Temperament
- Peaceful
- 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.
- Life expectancy
- 5-8 years
- This South American species, closely linked to the Brazilian coasts and characterized by benthic habits, has an average life expectancy in captivity ranging between five and eight years. To ensure maximum longevity for this fish, the aquarist must set up a mature tank with rocks rich in small invertebrates and a non-sharp sandy substrate at least six centimeters deep. Furthermore, a varied diet based on mysis, artemia, and chopped krill, administered in small doses several times a day, will prevent organic wasting and promote the maintenance of a strong immune system.
- Adult size
- 12 cm
- The catalog's scalar value is 12 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 27 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Halichoeres dimidiatus (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
- 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
- Moderate
- 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
- Oviparous
- 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
- Community
- The Halichoeres dimidiatus 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.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.6 ± 0.5 se
- Resilience
- Medium (1.4 - 4.4 years)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01148, b = 3.13
- VulnerabilityLow vulnerability (23 / 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.
