Cleaner Wrasse (Labroides dimidiatus)

What is a Cleaner Wrasse?

The Cleaner Wrasse (Labroides dimidiatus) is one of the most recognisable and ecologically fascinating fish on Indo-Pacific reefs — and one of the most controversial species in the saltwater aquarium trade. With its vivid electric-blue body and bold black lateral stripe, it is instantly identifiable. What makes it extraordinary is not its looks but its job: it sets up fixed cleaning stations on the reef where larger fish — including species that would normally eat a fish this size — queue up to have parasites, dead tissue, and mucus removed from their bodies.

This is a symbiotic relationship of remarkable complexity. Client fish signal their willingness to be cleaned with specific postures (head-up, fins spread, mouth and gills open), and the Cleaner Wrasse performs a characteristic bobbing dance before going to work. Even apex predators like groupers and moray eels hold still for the service. The Cleaner Wrasse is, in effect, the reef’s parasite-control system.

In captivity, however, this specialised lifestyle becomes the species’ greatest vulnerability. Most Cleaner Wrasses slowly decline in home aquariums because they cannot access the continuous stream of client fish and ectoparasites their bodies are built to consume. Be honest with yourself about this before purchasing.

Where do Cleaner Wrasses come from?

Labroides dimidiatus has one of the broadest distributions of any reef fish. It ranges across the entire Indo-Pacific — from the Red Sea and East Africa east across the Indian Ocean, throughout Southeast Asia, north to southern Japan, and east across the Pacific to the Tuamotu Archipelago in French Polynesia. It is absent from Hawaiian waters, which are served by a different cleaner species.

It inhabits coral reefs from the shallows down to about 40 m, establishing cleaning stations at prominent coral heads, rocks, or other conspicuous landmarks. A single station can service dozens of client fish species in a single day.

All Cleaner Wrasses sold in the aquarium trade are wild-caught. There is no commercial captive-breeding programme for this species. This adds an ethical dimension to the purchase decision: removing individuals from reefs depletes a genuine ecosystem service.

What size tank and setup does a Cleaner Wrasse need?

A minimum of 210 litres is recommended, and larger is substantially better — not because the Cleaner Wrasse itself needs vast swimming space (it reaches only about 11 cm), but because a larger tank with more resident fish provides more cleaning opportunities and therefore a better chance of the fish receiving adequate nutrition.

Key setup considerations:

• High stocking density helps. A Cleaner Wrasse in a sparsely stocked tank has fewer clients and will decline faster. Ironically, an already-crowded, parasite-prone system is the environment most likely to keep it occupied.
• Established reef. A mature system with robust biological filtration and stable chemistry is essential. This is not a fish for a new or cycling tank.
• Structure and hiding spots. Provide caves, overhangs, and coral heads where the fish can establish a cleaning territory and shelter at night. Cleaner Wrasses bury themselves in the sand or wedge into crevices to sleep.
• Tight-fitting lid. Like most wrasses, they can jump when startled.
• Peaceful community. Aggressive tank mates that harass the Cleaner Wrasse will prevent it from performing cleaning behaviour and add to its stress load.

What water parameters does a Cleaner Wrasse need?

Cleaner Wrasses require the stable, high-quality water chemistry of a well-maintained reef system. There is no margin for parameter swings in a fish already under the nutritional stress of captivity.

• Salinity: 1.023–1.025 SG (natural seawater equivalent). Hyposalinity treatment, sometimes used for ich, will harm this species.
• Temperature: 24–27 °C (75–81 °F). Keep it consistent; swings of more than 1 °C in a day are stressful.
• pH: 8.0–8.4, stable through the day. Wild reef water buffers naturally; monitor alkalinity in a closed system.
• Ammonia / nitrite: 0 ppm at all times. A cycled, mature system is mandatory.
• Nitrate: under 20 ppm; under 5 ppm preferred in a reef context.
• Phosphate: under 0.1 ppm.

Regular water changes (10–15% weekly or equivalent), a quality protein skimmer, and live rock for biological filtration are the foundations. Do not add a Cleaner Wrasse to a system that is not already running well.

What do Cleaner Wrasses eat?

This is the central challenge of the species. In nature, the Cleaner Wrasse’s diet consists almost entirely of ectoparasites (mainly gnathiid isopods and copepods), mucus, and loose or infected tissue gleaned from client fish. It is one of the most specialised feeding niches in the ocean.

In captivity, the fish must be transitioned to substitute foods, and not all individuals make this transition. Some adjustments that have worked for dedicated keepers:

• Frozen mysis shrimp — the most commonly accepted frozen food; try target-feeding small pieces near the fish’s patrol route.
• Copepod-enriched foods — pods and enriched pastes that mimic the nutritional profile of its natural prey.
• Parasitised tank mates — a heavily stocked, parasite-burdened tank gives the fish real work to do and may sustain it better than any substitute food.
• Feeding station training — some keepers report success using a feeding stick to deliver tiny mysis near the fish repeatedly until it associates the stick with food.

Be realistic. Many Cleaner Wrasses refuse all prepared foods entirely and starve within weeks to months despite excellent water quality. If your specimen is not actively accepting food within the first two weeks, seek advice from an experienced marine keeper immediately.

Is the Cleaner Wrasse reef safe — and what can live with it?

Yes, the Cleaner Wrasse is fully reef safe. It ignores corals, clams, and most invertebrates. Occasional mucus-nipping at coral tentacles has been reported in nutritionally stressed individuals, but this is uncommon and a signal to address the fish’s diet rather than a fundamental behavioural trait.

Good tank mates:

• Large, parasite-prone fish — tangs, angelfish, large wrasses, groupers, lionfish (if the tank is large enough). These provide the cleaning opportunities the fish needs.
• Other peaceful wrasses — fairy wrasses (Cirrhilabrus spp.) and flasher wrasses (Paracheilinus spp.) make compatible neighbours.
• Clownfish, gobies, cardinalfish — generally leave each other alone.
• Peaceful anthias — compatible in a large system.

Avoid:

• Aggressive or harassing species — dottybacks, some damsels, and dominant wrasses that will bully a Cleaner Wrasse and prevent cleaning behaviour.
• Very few resident fish — the biggest threat is not aggression but an empty cleaning schedule.

The “one per system” rule: Keep a single Cleaner Wrasse or a confirmed mated pair. Two unrelated individuals will fight. The dominant individual in a group is the male; if removed, the largest female will change sex to replace him — but this natural succession rarely plays out usefully in home aquariums.

How do you tell male and female Cleaner Wrasses apart?

The Cleaner Wrasse is a protogynous sequential hermaphrodite — all individuals are born female, and the dominant individual in a group transitions to male. This makes visual sexing unreliable without a known social context.

In a mated pair or group, the male is typically larger and may display slightly more intense colouration during courtship, but there is no definitive external marker like the ovipositor visible in, say, a betta. In practice, if you acquire a single juvenile and it eventually shows courtship behaviour or size dominance over a second individual, that individual has likely become male.

How do Cleaner Wrasses breed?

Captive breeding of Labroides dimidiatus is essentially not achieved in home aquaria and very rarely accomplished even in large public aquarium systems. The species is broadcast spawning: in the wild, the male courts females from his harem with rapid swimming displays, and spawning occurs in the water column at dusk, with eggs and sperm released simultaneously and fertilised eggs drifting in the plankton.

Replicating this in captivity requires enormous tanks, established mated pairs in excellent condition, and near-perfect water quality — and even then, raising the planktonic larvae through their extended development stages to settlement is an extremely advanced undertaking. This species is rated Very Hard for breeding.

What are common Cleaner Wrasse health problems?

Starvation / nutritional decline is by far the most common cause of death in captivity and should be considered the primary health concern from day one. A declining fish will become lethargic, lose colour, and may rest on the substrate before dying. Address food acceptance immediately.

Beyond nutrition, watch for:

• Marine ich (Cryptocaryon irritans) — white salt-grain spots; highly contagious in reef tanks. Quarantine all new fish. Note that hyposalinity treatment (a common ich remedy) cannot be used in a reef tank and will stress the Cleaner Wrasse.
• Marine velvet (Amyloodinium ocellatum) — gold-dust or velvety sheen; faster-progressing and more lethal than ich. Requires aggressive treatment in a hospital tank.
• Brooklynella — a ciliate infection sometimes called clownfish disease but not limited to clownfish; causes rapid tissue decay.
• Bacterial infections — secondary to stress, injury, or poor water quality. Manifest as lesions, fin damage, or cloudy eyes.

Maintain a quarantine tank for all new additions. The Cleaner Wrasse itself is not more disease-prone than other marines if nutrition and water quality are good, but a nutritionally stressed individual has a compromised immune system and will fall ill more readily.

How long does a Cleaner Wrasse live?

In the wild, Labroides dimidiatus lives approximately 4–5 years, with some records suggesting longer. In captivity, the realistic expectation is 2–5 years for a well-managed individual, with the lower end being far more common due to nutritional challenges.

A Cleaner Wrasse that is eating reliably, in a large, well-stocked reef with excellent water quality, may approach or exceed the wild lifespan. The majority, however, do not reach the two-year mark. This sobering reality is why many experienced reef-keepers recommend against the species for all but the most advanced, large-format systems — and why honest evaluation of your tank’s suitability is essential before purchase.