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Livestock · Wrasses

Six Line Wrasse

Pseudocheilinus hexataenia

A busy, colourful wrasse that hunts pest snails and flatworms — but can turn a bully.

Difficulty: Beginner–IntermediateSemi-aggressive fishReef-safe

The six line wrasse (Pseudocheilinus hexataenia) is a busy, jewel-striped little wrasse that hunts pest snails, flatworms and bristleworms through the rockwork — a genuine helper. The catch: it's peaceful as a youngster but turns territorial with age, so it goes in LAST, one per tank, under a tight lid (it's a jumper).

Good to know: Can become aggressive as it settles — add it LAST.
📊 What keepers actually ask: The six-line's reputation is split: keepers love it for pest control and warn about its temper. Both are true — so we tell you exactly how to get the good without the bad (add last, one only).

Care at a glance

Adult sizeAbout 3–4 in (7.5–10 cm).
Minimum tank~30–55 gallons with plenty of live rock to forage through and hide in.
Temperature72–78°F (22–26°C).
pH8.1–8.4.
Specific gravity1.023–1.026.
Other targetsLots of rockwork to hunt through and sleep in; keep nitrate low.
DietCarnivore — frozen mysis, brine and krill plus small marine preparations, 2–3× a day. It also hunts pests (pyramidellid “clam-parasite” snails, flatworms, bristleworms, pods) — but this varies a lot: some are voracious pest-hunters, others ignore pests once used to easy frozen food.
TemperamentPeaceful as a juvenile, but develops a real semi-aggressive, territorial streak with age — it harasses newcomers and fish of similar shape. Keep ONE per tank, and add it LAST, after the calmer fish are settled.
Reef-safeReef-safe with corals — but not fully invert-safe: it can pick at ornamental crabs, small starfish, clams, and desirable pods/small shrimp.
Natural rangeIndo-West Pacific and the Red Sea.
Beginner-friendly, done right. Not hard to keep — hardy, and a great pest-hunter — but it earns its Beginner–Intermediate rating on temperament, not care. Add it last, keep just one, and lid the tank, and it's brilliant. Add it early or keep two, and it can bully a peaceful community.
Planning your stock list? Before you buy, run your tank and wish-list through our free stocking & tank-size calculator — it checks this fish's minimum tank and shoal size and flags any aggression clash, so you don't overstock.

The fish store gets these wrong

Common myths, kindly corrected — no shame for having believed them.

  • “A six line wrasse will clear my flatworms/pests.” Sometimes — but it's hit and miss. Some hunt pests voraciously; others, used to easy frozen food, ignore them. Treat pest control as a bonus, not a guarantee.
  • “It's reef-safe, so it's invert-safe too.” Not quite — it's safe with corals but may pick at ornamental crabs, small starfish, clams, and desirable pods/shrimp.
  • “Add it whenever.” No — add it LAST. A settled six line bullies newcomers, so it should be among the final (and to a calm, established tank).

Before you buy

  • Add it LAST, once your peaceful fish are established.
  • One per tank — they don't tolerate their own kind (or similar-shaped fish).
  • Use a tight lid — it's an accomplished jumper.
  • Give it plenty of live rock to hunt and hide in.

Quarantine and get help if…

We can't diagnose from a photo — but these are the signs to stop watching, quarantine, and get an aquatic vet or an experienced reefer's eyes on it:

  • White salt-grain spots, flashing, or rapid gill-breathing (possible ich or velvet).
  • Cloudy skin patches, clamped fins, or gasping at the surface.
  • Hiding and refusing food for days, or a hollow belly.
  • Any new fish added without quarantine.

Never

  • Never add a six line wrasse early — it bullies later additions.
  • Never keep two in one tank.
  • Never run an open-top tank — it jumps.
  • Never assume it'll definitely eat your pests — it's variable.
  • Never add it to an uncycled tank.

Common six line wrasse questions

Is the six line wrasse aggressive?

It becomes so with age. Six line wrasses are peaceful as juveniles but develop a strong territorial streak, harassing newcomers and similar-shaped fish. The fix is simple: add it LAST, and keep only one per tank.

Will a six line wrasse eat pests like flatworms and pest snails?

Often, yes — they hunt pyramidellid (clam-parasite) snails, flatworms, bristleworms and pods. But it's variable: some are voracious, others ignore pests once used to frozen food. Treat it as a helpful bonus, not a guaranteed cure.

Is the six line wrasse reef-safe?

Yes with corals. It's not fully invert-safe, though — it may pick at ornamental crabs, small starfish, clams, and desirable pods or small shrimp.

Do six line wrasses jump?

Yes — they're accomplished jumpers. A tight-fitting lid or mesh cover is essential.

What size tank does a six line wrasse need?

About 30–55 gallons with plenty of live rock to forage through and hide in. The rock matters as much as the volume — it hunts and sleeps in the reef structure.

Sources & further reading

This guide was written and fact-checked against these authorities. It's honest, general guidance — not a diagnosis, and not a substitute for an aquatic vet or your own test kit:

Written and fact-checked by The Coralkin Team against marine-aquarist and veterinary sources — if your six line wrasse shows a red-flag sign above, quarantine and get an aquatic vet or an experienced reefer's eyes on it. We never guess a care number.

🔬 Review status: team-written and fact-checked against cited sources · not yet reviewed by a marine vet. How we research & fact-check →

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