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Care guide · Marine fish

Six-line wrasse

Pseudocheilinus hexataenia

Six-line wrasse — Pseudocheilinus hexataenia
Photo: Lonnie Huffman · Source · CC BY 3.0Resized and compressed; no cropping or colour changes.

The six-line wrasse is small but distinctly active. Pseudocheilinus hexataenia continually searches rockwork for tiny prey and has clear longitudinal stripes and a greenish tail. This may seem useful when unwanted organisms appear, but the fish is not a selective pest-control product. Desired small shrimp, worms and other accessible animals may also be at risk. An established individual can intimidate timid fish. Choose it for its complete care requirements and companions, not as a quick cure for an infestation. A spacious mature aquarium with many rock routes and a practical way to resolve conflicts suits it better than a small busy reef. Modest adult length makes it neither automatically peaceful nor beginner-friendly. Consider its likely impact on firefish and other wrasses particularly carefully before purchase.

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At a glance

Adult size
Approximately 8 cm
Aquarium length
At least 100 cm
Minimum aquarium volume
At least 250 L
Temperature
24–26 °C
Specific gravity (SG at 25 °C)
1.024–1.026 SG
Salinity
32–35 ppt
pH
8.1–8.3
Difficulty
Moderate
Temperament
Aggressive, May jump
Diet
Carnivore
Swimming zone
Middle
Reef safety
Reef safe with caution
Suitable for beginners
No
Social needs
Solitary
Keeping conspecifics
Prefer one individual

Cautious husbandry guidance for adults, not a complete stocking calculation. Assess tank length, layout and the entire community together.

About this species

Adults grow to about 8 cm. Six conspicuous lengthwise stripes and the marking near the tail base help identify it. Other striped wrasses may have very different requirements, so use the scientific name. This is not a cleaner wrasse intended to cure diseases in tankmates. Constant searching is normal, whereas endlessly repeating one route along the glass calls for assessment of stress and useful layout. Ask about familiar food and previous interactions with neighbours.

Natural habitat

The species lives on tropical Indo-Pacific reefs with crevices and extensive hard surfaces, searching between structures for small animal prey. Provide mature rockwork with several routes, resting sites and controlled feeding. Do not automatically borrow another wrasse’s requirements: sleeping behaviour and the need to bury in sand vary. A secure rocky crevice and sufficient functional space matter more than generic family-wide advice for this particular fish.

Aquarium and layout

Use approximately 250 L and 100 cm of length as a cautious planning threshold. Specialist sources disagree on minimum volumes; activity and territory justify choosing the roomier end here. Even a larger crowded tank can be unsuitable for shy neighbours. Interrupt sightlines and create several passages while retaining open swimming space. Cover all gaps and protect intakes. Plan a practical removal method: a fast small wrasse can be difficult to catch in dense rockwork if a pairing fails.

Water conditions

Maintain stable tropical seawater and measure temperature, pH and salinity. Feeding an active fish adds waste; check ammonia/ammonium and nitrite after additions or changed behaviour and follow nitrate over time. Replace evaporation with suitable fresh water. Prepare replacement seawater beforehand and check it before use. A supposed pest problem that prompted purchase must not become an excuse to neglect normal water quality or feeding.

Behaviour and group size

Territorial aggression is a substantial concern. A six-line wrasse may be much fiercer towards quiet or similarly shaped fish than its size suggests. Do not establish it early in a limited tank intended to receive vulnerable fish later. Watch persistent pursuit, injury and neighbours afraid to eat. More rocks or additional food cannot guarantee a solution. Sometimes one animal must move to another suitable aquarium.

Social behaviour and conspecifics

Keep one specimen as the standard. More conspecifics or similar wrasses require a specifically assessed spacious setup and experienced judgement. Entering two fish in a planner must not automatically establish a pair. Individual variation does not remove the need for caution. A temporarily calm fish may become dominant after claiming territory. Arrange alternative accommodation before trying a risky combination rather than relying on good behaviour continuing indefinitely.

Feeding

The diet is mainly animal-based. Offer appropriate small marine foods, including suitable mysis, enriched brine shrimp and accepted complete feeds, as a varied ration. Rock hunting does not mean an aquarium supplies enough prey indefinitely. Check condition and intake. Do not expect the fish to eat only one unwanted organism and then survive without added food. Products are linked only once application, form and particle size have been adequately assessed.

Reef safety

The six-line wrasse generally leaves coral tissue alone, but receives a conditional reef verdict because a reef contains more than corals. Small invertebrates may be at risk. This distinction prevents favourable advice about polyps from being mistaken for permission to add ornamental shrimp or tubeworms. Feeding cannot switch off natural foraging. Assess the whole population rather than asking only whether corals are likely to be eaten.

Stony corals

Generally low risk

Coral tissue feeding is not part of the documented normal feeding behaviour. Monitor contact and individual behaviour; low risk is not a guarantee.

Soft corals

Generally low risk

Coral tissue feeding is not part of the documented normal feeding behaviour. Monitor contact and individual behaviour; low risk is not a guarantee.

LPS corals

Generally low risk

Coral tissue feeding is not part of the documented normal feeding behaviour. Monitor contact and individual behaviour; low risk is not a guarantee.

SPS corals

Generally low risk

Coral tissue feeding is not part of the documented normal feeding behaviour. Monitor contact and individual behaviour; low risk is not a guarantee.

Anemones

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Keeping with other fish

A firefish is a risky neighbour because of timidity and feeding competition. Small gobies and quiet cardinalfish can also be pressured. Ocellaris or royal gramma are not automatically safe: their own territories may create additional conflict. Large active fish bring greater space needs too. Relationship cards distinguish conditional from discouraged combinations. A large predator capable of injuring the wrasse is not a sensible solution to the wrasse’s aggression.

Keeping with invertebrates

Small ornamental shrimp, accessible worms and other tiny rock-dwellers fit its hunting behaviour. Small snails may also be investigated as prey. A large adult cleaner shrimp differs from an offspring, but there is no universal guarantee for it either. Assess the exact species and size, including vulnerability during moulting. Insufficiently documented categories remain unknown. Calling the fish pest control must not hide the risks to wanted animals.

Large adult cleaner shrimp

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Small ornamental shrimp / juveniles

High risk

This active hunter searches rockwork for small animals. Small ornamental shrimp and other accessible prey are at risk despite a reef-safe label.

Crabs

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Hermit crabs

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Snails

Risk depends on conditions

Small snails may be investigated as prey. One larger snail being ignored does not establish safety for every species or size.

Feather duster worms

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Clams / giant clams

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Starfish

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Sea urchins

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Small fish

Insufficient evidence

Insufficient species-specific evidence was found for this animal group. A general reef-safe label does not establish safety.

Breeding

Reproduction and larval rearing require specialist conditions. Putting two adults together is no simple breeding method and can create serious social problems. This guide does not offer an inadequately checked home protocol with fixed egg numbers or reliable rearing times. Concentrate first on one healthy fish in an appropriate community. Breeding work requires further species-specific research, space and suitable larval food.

Possible problems

Watch every animal exposed to the wrasse’s activity, not only the wrasse. Hidden neighbours, injured shrimp or sudden small-invertebrate losses need investigation. Not every missing snail was eaten; assess water quality and other explanations too. Persistent intimidation often warrants separation rather than waiting. Keep the cover closed during and after maintenance. A peaceful first week provides no lifetime guarantee of compatibility.

Sources & review

This care guide draws on several specialist sources and was last checked on .

View the sources