Saltwater Fish

Sixline Wrasse

Pseudocheilinus hexataenia

Active, jewel-toned hunter of reef pests · Beginner

Lifespan: 4-7 years
Adult size: 7-8cm (3in)
Min. habitat: Aquarium 110L+ / 30gal+
Social needs: One per tank in most systems
Diet: Carnivore, micro-invertebrates
Time: Low
Cost: Medium

Overview

The Sixline Wrasse is a small, fast, jewel-toned fish striped orange and blue, popular for its hardiness and appetite for reef pests.
It is constantly active, darting through rockwork in search of food.

It is reef-safe and helps control pyramidellid snails and some flatworms.
Easy to keep, it suits beginners, though its bold temperament can grow more aggressive as it matures.

Housing

House in an established reef of at least 110L (30 gallons) with abundant live rock full of crevices to hunt and shelter in.
A mature tank with a good population of micro-invertebrates provides natural foraging.

Keep temperature 24-27C (75-81F), salinity 1.024-1.026, pH 8.1-8.4, and ammonia and nitrite at zero.
Plenty of rockwork lets this active fish exercise its natural hunting behaviour.

Diet

A carnivore that hunts copepods, amphipods, small worms, and other micro-invertebrates among the rocks.
Supplement with frozen mysis and brine shrimp, marine flakes, and pellets once or twice daily.

A mature tank with a healthy pod population supports natural grazing between feedings.
It readily accepts prepared foods, making it simple to keep well-fed and active.

Health

Hardy and disease-resistant, one of the more forgiving marine fish, though quarantine remains best practice.
Stable water and a varied diet keep it healthy and well coloured.

Watch for hiding, faded colour, or reduced appetite as signs of stress or poor conditions.
It can also jump, so a secure lid prevents the most common cause of accidental loss.

Temperament

Active and bold, it becomes increasingly territorial and aggressive with age, sometimes harassing newly added or timid fish.
Add it last to a community so existing fish are established, and keep only one per tank.

Reef-safe with corals and most invertebrates, it leaves desirable inverts alone while hunting pests.
Its assertive nature means careful tankmate selection in smaller or peaceful systems.

A good fit for

Beginners wanting a hardy, active fish
Reef tanks needing pest control
Mature tanks with healthy pod populations
Keepers wanting colour and movement

Common mistakes to avoid

Grows territorial and aggressive with age
Add last so it cannot dominate
Known jumper; needs a secure lid
May bully timid or newly added fish

Is your enclosure big enough?

Minimum volume110 litres (29 US gallons)

CompanyMust be housed alone. One per tank in most systems

Check your own enclosure against this

Is this urgent?

In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.

Go now

Any detectable ammonia or nitriteWater change now with matched, mixed and aerated saltwater. Stop feeding. Directly toxic, and a marine system has less margin than a freshwater one.

Now

Temperature or salinity has moved sharplyCorrect slowly, over hours, not minutes. Check the heater and the top-off. The speed of the change does the damage. Correcting fast repeats the injury in the other direction.

Now

Rapid gilling, or a fish hanging in the flow breathing hardIncrease aeration and check temperature and salinity. Warm water holds less oxygen, and a heater failure shows up here first.

Now

Today

White spots, or a fine dusting like icing sugarIdentify which parasite before treating. Most reef tanks cannot be treated in place. The two common parasites look similar and need different handling; velvet can kill a tank in days.

Today

Corals closed for more than a day, or receding tissueTest alkalinity first, and compare it against the last reading rather than a target. Unstable alkalinity is the most commonly cited coral killer, and a swing shows up in the trend, never in a single point.

Today

A new fish added without quarantine now looks unwellRemove it to a separate system today if you can. Nearly every wipeout in a reef tank traces back to a skipped quarantine.

Today

Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.

This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.

What it really costs

Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.

Work out the cost of a sixline wrasse

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