Sixline Wrasse
Pseudocheilinus hexataenia
The Sixline Wrasse features six distinct, horizontal blue lines on a vibrant green-brown body and a slender, elongated form.
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About the Sixline Wrasse
The Sixline Wrasse is that nonstop little reef torpedo that weaves through rockwork all day hunting tiny critters. It's awesome for picking at pests like small worms/flatworms, but once it settles in it can get pretty territorial-especially in smaller tanks or with similar-shaped fish.
Also known as
Quick Facts
Size
10 cm
Temperament
Semi-aggressive
Difficulty
Intermediate
Min Tank Size
20 gallons
Lifespan
5-10 years
Origin
Indo-Pacific
Diet
Carnivore/micro-predator – meaty frozen foods (mysis, brine), quality pellets/flakes, and naturally hunts small crustaceans/reef pests
Water Parameters
24-28°C
8-8.4
8-12 dGH
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Calculate heater sizeCare Notes
- Give a Sixline a rock-packed tank with lots of little caves and overhangs-when they feel exposed, they get way more cranky and chase-y.
- Keep the basics steady: ~1.020-1.025 specific gravity, ~75-82°F (24-28°C), pH ~8.0-8.4; they're hardy, but can act stressed when salinity swings.
- Feed small meaty stuff 1-2x/day (mysis, brine, chopped shrimp, quality pellets); they're constant pickers, so a single huge feeding doesn't suit them.
- They'll hunt pods and tiny pests in the rockwork, but don't buy one expecting it to "solve" flatworms forever-think bonus help, not a guarantee.
- Add them later in the stocking order; once a Sixline claims the tank, it often bullies new additions, especially timid fish and similar-shaped wrasses.
- Avoid mixing with other Pseudocheilinus wrasses or shy fairy/flasher wrasses in smaller tanks-Sixlines love being the neighborhood cop.
- Use a tight lid/mesh top: they can and will jump, especially the first week or if they get spooked by lights or a bigger fish.
- Breeding happens in pairs with quick spawning runs near dusk, but raising the larvae is a whole plankton-feeding project-cool to watch, tough to pull off.
Compatibility
Good Tankmates
- Other tougher reef fish that mind their own business, like clownfish (ocellaris/percula) or chromis - the sixline will usually just do its patrol-and-peck routine and ignore them after the pecking order's set.
- Mid-water swimmers that aren't timid, like fairy/flashers wrasses (Cirrhilabrus/Paracheilinus) in a decent-sized tank with lots of rockwork - add the sixline last if you can so it doesn't claim the whole reef as 'mine.'
- Dwarf angels (flame/coral beauty, etc.) - generally a solid match since they're confident and not easily bullied, and they don't compete directly with the sixline's 'micro-pest hunter' vibe.
- Tangs and rabbitfish (yellow tang, kole tang, foxface) - different lanes: they graze, the sixline hunts pods. Usually very workable if the tank isn't cramped.
- Hawkfish and blennies that can hold their ground (flame hawk, lawnmower blenny) - the sixline might posture a bit, but these guys aren't typically pushovers.
- Peaceful gobies that stick to their burrow (watchman goby types) - often fine as long as the goby isn't tiny and you've got lots of hiding spots so the sixline can't constantly 'inspect' it.
Avoid
- Other sixline wrasses (or most Pseudocheilinus wrasses) - they almost always turn it into a turf war unless you've got a big system and you're doing a very deliberate pairing plan.
- Shy, slow, easily stressed fish like firefish and small assessors - sixlines love to 'manage' them, which translates to nonstop chasing in a lot of tanks.
- Newly added small wrasses and delicate sand sleepers (leopard wrasses, some Halichoeres when first introduced) - a settled-in sixline can harass them hard, especially if it was there first.
- Tiny, gentle fish like small cardinals or juvenile gobies in tight rockwork - not usually eaten, but they can get pinned into hiding and stop coming out to feed if the sixline is in a mood.
1) Where they come from
Sixlines are little Indo-Pacific reef wrasses. In the wild they spend their whole day weaving through rock and coral branches, picking at tiny bugs you’ll never notice. That “always hunting” vibe is basically their whole personality in a tank too.
2) Setting up their tank
Give them a reef-style setup with lots of live rock and nooks. They don’t just like hiding spots—they use the rockwork like a highway system. If your aquascape is a couple of big boulders with open sand, they’ll act way more stressed and edgy.
Tank size-wise, people keep them in smaller tanks, but you’ll have a much easier time in a 40 breeder-ish footprint or bigger. In tight quarters they can turn into the “tiny fish, big attitude” stereotype fast.
- Rockwork: lots of holes, caves, and branching areas to weave through
- Lid: a real lid (mesh is fine) — they can and do jump
- Flow: moderate is fine; they’re agile and will play in it
- Maturity: they’re happiest in a tank that’s been running a bit and has microfauna to hunt
If you’re planning a “peaceful community reef,” add the sixline last (or don’t add one at all). Once they claim the rockwork, they can get bossy with new arrivals.
3) What to feed them
They’re carnivores that graze all day. The biggest mistake I see is feeding them like a once-a-day “regular fish.” They’ll survive, but they do better with smaller, more frequent feedings—plus they stay less cranky when their belly isn’t empty.
- Frozen: mysis, finely chopped shrimp, calanus/cyclops, reef blends
- Pellets: small marine pellets work great once they recognize them
- Live (nice for new/shy fish): live brine enriched, copepods
If your sixline ignores prepared food at first, don’t panic. Try a little frozen cyclops/calanus in the flow so it looks “alive,” and feed near the rockwork where they already hunt.
4) Behavior and tankmates
They’re busy, curious, and always on patrol. That’s the charm. The flip side is they can be territorial, especially in smaller tanks or if they’ve been the “top wrasse” for a while.
As a general rule, they’re safest with fish that won’t be easily intimidated, and not with other small, similar-shaped hunters they’ll see as competition.
- Usually fine with: clownfish, tangs (in appropriate tanks), cardinals, many gobies/blennies (watch timid ones), rabbitfish
- Can be a problem with: other wrasses (especially small/peaceful ones), dottybacks, timid firefish, new small gobies added after the sixline
- Reef/inverts: generally reef-safe, but don’t trust them with tiny ornamental shrimp (sexy shrimp, very small cleaners) — some sixlines learn they’re snacks
People buy sixlines to “fix pests” (flatworms, nudis, etc.). Sometimes it works, sometimes they ignore the problem and just become the tank’s hall monitor. Think of pest control as a bonus, not the plan.
5) Breeding tips (what’s realistic at home)
They do spawn in captivity, but raising the babies is the hard part. Like a lot of marine fish, the larvae are tiny and need specialized live foods and a dedicated rearing setup. Most hobbyists don’t intentionally breed them in a display tank.
If you ever keep a known pair (not easy to sex reliably), the best “breeding tip” is honestly just: stable reef, heavy feeding, and lots of rockwork. But if your goal is raising fry, you’re looking at a whole separate project.
6) Common problems to watch for
- Jumping: they launch through tiny gaps—cover overflows and corners
- Aggression creep: they can start out fine and later decide they own the tank
- Bullying new additions: especially small fish added after they’ve settled in
- Parasites: they can still get marine ich/velvet—quarantine is worth the effort
- Starving slowly: in new/sterile tanks with light feeding, they can lose weight even if they’re “active”
If a sixline turns into a bully, catching it in a rock-filled reef is not fun. Plan ahead: use a fish trap early, or be ready to pull a bit of rockwork if you have to. Waiting until it’s a full-blown jerk makes the whole job harder.
A well-fed sixline is usually a better neighbor. I’ve had the best luck doing two small feedings a day and keeping the rockwork complex enough that other fish can stay out of its face.
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