Four-line Wrasse
Pseudocheilinus tetrataenia
A small, brightly colored marine wrasse widely recognized for its tireless hunting of nuisance pests within mature reef aquarium setups.
Water Temperature
24 - 27 °C
pH Value
8.1 - 8.4
Water type
Marine
Tank level
Bottom and middle
Adult size
7.5 cm
Minimum tank volume
>= 100 L
Minimum group
>= 1
GH
15 - 25 dGH
KH
8 - 12 dKH
Species description
Geographical Origin and Habitat: This species is native to the coral reefs of the Indo-Pacific Ocean, ranging from the Ryukyu Islands to Hawaii, the Marshall Islands, and the Tuamotu Archipelago. It typically lives among coral branches at depths between 6 and 44 meters.
Taxonomy and Morphology: Belongs to the family Labridae, genus Pseudocheilinus. The body is elongated and laterally compressed, reaching a maximum size of about 7.5 cm (3 inches). It features distinctive red eyes split by a white stripe.
Social Behavior: Solitary and markedly territorial towards conspecifics or similar wrasses. Swims actively through rockwork in search of small crustaceans.
Coloration and Sexual Dimorphism: Features four bright horizontal neon-blue stripes over a red-orange body that fades to olive green on the belly. Sexual dimorphism is not prominent, though dominant males may display brighter colors during courtship.
Care, breeding and tankmates
Aquarium Setup: Requires a tank of at least 100 liters with abundant live rock providing numerous caves and crevices for shelter. A tight-fitting lid is essential to prevent jumping.
Diet and Feeding: Active carnivore. In captivity, it consumes mysis, frozen brine shrimp, small pellet foods, and naturally controls small pests like flatworms and parasitic snails.
Water Quality: Requires stable marine parameters: temperature of 24-27°C (75-81°F), stable pH between 8.1 and 8.4, specific gravity between 1.022 and 1.025, GH 15-25, and KH 8-12.
Compatibility and Cohabitation: Reef-safe. May harass small ornamental crustaceans like shrimp and target similar small wrasses, but is completely ignored by corals.
Aquarium Breeding: Extremely rare in the aquarium hobby. Releases pelagic eggs into the water column; larval rearing is highly technical and requires specialized live food cultures.
Risks and Diseases: Robust fish once acclimated. Can suffer from ectoparasites like Cryptocaryon irritans under stressful conditions. High risk of jumping when startled.
Geographic Origin and Distribution
This species is native to the coral reefs of the Indo-Pacific Ocean, ranging from the Ryukyu Islands to Hawaii, the Marshall Islands, and the Tuamotu Archipelago. It typically lives among coral branches at depths between 6 and 44 meters.
Origin
Tropical oceans and reefsNorth AmericaEast Asia
Fish profile
- Temperament
- Semi-aggressive
- They are highly active, curious, and can be quite territorial. They are known to harass peaceful or slower-moving fish, especially new additions. It is highly recommended to add them as the last fish in a community tank to minimize aggressive behavior.
- Diet
- Planktivore
- They are strict carnivores that spend their day hunting small crustaceans on live rock. In captivity, they will readily take frozen mysis, brine shrimp, and high-quality carnivore flakes or pellets. They are also known to actively hunt and eat pest flatworms and small nuisance snails.
- Life expectancy
- 5-7 years
- The Fourline Wrasse typically lives for 5 to 7 years in captivity under optimal care. To support this lifespan, they require a stable marine environment, high water quality, and a varied diet. Territorial stress from aggressive tankmates or fighting with other wrasses can shorten their lifespan. They are generally hardy and disease-resistant once they adjust to the aquarium.
- Adult size
- 7.5 cm
- The catalog's scalar value is 7.5 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 7.5 cm for this species, recorded as total length (TL). The taxonomic record consulted is Pseudocheilinus tetrataenia (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
- They should be kept singly in the home aquarium due to their high conspecific aggression. They will not tolerate another Four Line Wrasse or closely related species. Keeping more than one is only possible in extremely large systems with abundant hiding places.
- Feeding frequency
- 2-3 times daily
- They should be fed one to two times daily with small portions. They will constantly forage for microfauna in the aquarium, which supplements their diet naturally. An established aquarium with plenty of mature live rock is ideal for their grazing habits.
- Bioload
- Low
- The Four Line Wrasse has a small and very manageable bioload. They do not produce excessive waste, making them suitable for smaller reef setups. Standard filtration and a regular water change schedule are completely adequate.
- Flow
- Stagnant
- They prefer moderate water movement that mimics the currents over natural reef structures. They are agile swimmers capable of handling high flow without issue. Ensuring good circulation helps keep the tank clean and oxygenated.
- Jump risk
- Yes
- Like all species in the Pseudocheilinus genus, they are notorious jumpers. A tight-fitting, secure lid or mesh screen is absolutely vital to prevent them from leaping out. They can escape through incredibly small openings, so double-check all gaps.
- Reproduction
- Oviparous
- They are pelagic spawners, releasing eggs and sperm directly into the water column. They are protogynous hermaphrodites, and dominant females will transition to males if needed. There are no successful reports of captive breeding due to the complicated pelagic larval stage.
- Compatibility & tankmates
- Reef safe with caution
- They are fully reef safe regarding corals and sessile invertebrates. However, they may predate on small ornamental shrimp or small crabs. They can be very aggressive towards other wrasses and timid fish, so choose tank mates carefully.
- Tank level
- Middle/Bottom
- They are highly active fish that predominantly stay in the middle to lower levels. They are closely associated with the aquascape, constantly darting in and out of the live rock. They require numerous caves and crevices for hunting, hiding, and sleeping.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.3 ± 0.4 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5078
- Bayesian Length-Weight
- a = 0.01072, b = 3.03
- 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.
