Six Line Wrasse

The popular and (sometimes) pugnacious six line wrasse

Pseudocheilinus hexataenia, commonly known as Six Line Wrasse or Six Stripe Wrasse, is one of the most popular saltwater fish you can find in stores and online. One look at them and it isn’t hard to see why they are so popular. This article will cover some of what makes this fish so interesting and answer a few of the most common questions about keeping them in a reef tank.

What is the minimum six line wrasse tank size?

The six line wrasse, Pseudocheilinus hexataenia, requires a minimum tank size of 55-gallons (~208 liters), for maximum health. Adults will grow to about 3-inches in total length, but they require open space for swimming. 

Feel free to jump ahead to review some of the most frequently asked questions:

Six line wrasse (Pseudocheilinus hexataenia)

Whether they are blue with orange stripes or orange with blue stripes, I’m not quite sure, but the bottom line (did you like that pun?) is that they are very attractive fish.

My favorite aspect about these fascinating fish is to watch their eyes as they hunt. Their eyes dart around and remind me of a chameleon that way. They are generally inexpensive and widely available and are perpetual motion machines zooming around the tank without a care in the world.

How big does a six line wrasse get?

The typical size to see a six line wrasse at a local fish store is in the 1-2 inch range, but they will grow to between 3 and 4 inches in total length when fully grown.

6 line wrasse near gorgonian coral

Ideal habitat

Pseudocheilinus hexataenia originates in the Central and Indo-West Pacific Ocean, and the Red Sea as well. These fish can also be found in the northern part of New South Wales, the northern part of the Great Barrier Reef, and areas around northwestern Australia.

Indo-Pacific biogeographic region map-en

They are hardy fish that are relatively easy to keep in a saltwater aquarium. A relatively small fish, they tend to stay under 3 inches long, but they need a lot of open water in which to swim, so they are best kept in a tank that is at least 55-gallons in volume.

According to a 2021 survey, the most common aquarium size was between 55 and 90 gallons.

Six stripes are boldly-mannered fish, naturally, but they also tend to do best when kept with a moderate amount of live rock. They will dart in and out of the aquascape for protection and will scour the rock looking for a tasty morsel to eat.

Six-line wrasse

Is the Six Line Wrasse reef safe?

The Six Line Wrasse is reef safe in 81.7% of aquariums, according to a 2021 survey. 18.2% observed compatibility issues with either anemones, corals, clams, crabs, or starfish. Of all the invertebrate issues, 47% were between the Six Line Wrasse and crabs.

Source: Saltwater Aquarium Blog survey data October 2021.

Survey answersPercentage
Completely reef safe81.7%
Not reef safe (observed compatibility issues)18.2%

Among the 18.2% of reports that the Six Line Wrasse was not reef safe in their tank, the following issues were reported:

Anemones7%
Corals13%
Clams13%
Crabs47%
Starfish20%
The most common reef safe compatibility issues were with crabs

Do six line wrasses eat coral?

Six line wrasses do not eat coral. Their natural behavior is to hunt for tiny invertebrates like worms, copepods, snails, or other meaty foods that are living among the coral tissue. Even though the fish is not eating the coral, damage and stress to the coral could still be a result.

In the 2021 study, 13% of reef safety and compatibility issues with the Six Line Wrasse involved challenges keeping them with corals.

Note the six stripes on the body of this fish

Feeding and nutrition

Pseudocheilinus hexataenia is a carnivorous fish, spending most of its time picking at live rocks in search of small worms (like bristle worms), parasites, and crustaceans.

Most individuals will accept standard saltwater fish food, like flakes, pellets, or tablets, but what they would appreciate most is frozen food and even small live food.

These are very active fish. If possible, try to feed them 2-3 times a day.

Do six line wrasses eat flatworms?

Six line wrasses will eat some flatworms and segmented worms, like the bristle worm. However, one should not expect that a single individual will be sufficient to rid your aquarium of these pests completely. There also appears to be variability in how eager an individual fish is to eat them.

Some eat them voraciously, others seem to ignore them.

male and female six stripe fish

How many per tank?

The vast majority of aquarium owners keep a maximum of 1 Six Line Wrasse per tank. 51 of 57, or 89% reported keeping just 1 individual in their tank, 9% kept 2, and 2% had 3.

Behavior and tank mates for the 6 line wrasse

Compatibility is one of the biggest issues with keeping the six-line wrasse because they can be semi-aggressive and pester other fish, especially other members of the wrasse family, including:

They can stress out shy fish so much they may succumb to parasites or even die.

This isn’t just speculation, take a look at these data:

The chart above shows the number of times a fish type was indicated as compatible with the six line wrasse, in blue, and the number of times it was indicated incompatible, in red.

At a glance, that means, the longer the blue line, the more times an actual aquarium owner observed the peaceful coexistence of the two fish.

The longer the red line, the more times a different aquarium owner (most time) observed significant compatibility issues between the two types of fish.

Key compatibility takeaways from this survey:

  1. There were compatibility issues with each of the top 10 most popular saltwater fish types
  2. The most issues were with other wrasses, tangs and blennies

The chart above shows the magnitude of the potential problems, at a glance. But if we focus now on the incompatibility rate of the fish pairings with the highest number of reported issues, we start to see some actionable data emerge:

Fish typeProbability of an issue

Wrasses
1 in 3
Dottybacks1 in 5
Basslets/Grammas1 in 8
Blennies1 in 8
Tangs1 in 10
Gobies1 in 11
Angelfish1 in 11
Cardinalfish1 in 12
Chromis1 in 12
Clownfish1 in 25

The data above indicate the magnitude of the issues reported among the most commonly reported fish types, but those were not the only compatibility issues that were reported. The six line wrasse was indicated as incompatible, at least once, 26 out of the 32 possible saltwater fish types surveyed.

Fish typeCompatibleIncompatible% Incompatible
Wrasses181138%
Tangs45510%
Blennies38512%
Gobies4349%
Angelfish4149%
Dottybacks17419%
Clownfish6534%
Cardinalfish3638%
Chromis3438%
Basslets/Grammas22312%
Dartfish11321%
Filefish6333%
Damselfish2827%
Butterflyfish13213%
Boxfish1267%
Groupers1267%
Grunts/Sweetlips02100%
Anthias1815%
Rabbitfish1317%
Dragonets8111%
Hawkfish4120%
Jawfish3125%
Lionfish3125%
Eeels2133%
Pufferfish2133%
Hogfish1150%
Triggerfish800%
Assessors or Marine Bettas500%
Pipefish200%
Tilefish200%
Seahorses100%
Squirrelfish100%
There was at least one report of compatibility issues between the six stripe wrasse and nearly every other fish type in the survey. Now, the sample size of each of the reports of incompatibility starts to get small, making it difficult to project out to a broader population, but this does suggest that fish type alone is not the only driver of compatibility issues.

Tank size is correlated with aggression and incompatibility, but not the way you may expect

The most surprising conclusion from the survey data is that tank size matters when it comes to aggression and compatibility issues with the Six-line wrasse, and there were fewer issues in the smaller tanks. Wait, what? See for yourself:

Size of the tank does appear to be correlated with compatibility issues, but why? Piecing each of the individual conclusions from the survey together, a pattern is starting to emerge. While it appears that certain types of fish are more likely to cause problems than others, the fact that someone proactively indicated they were incompatible in a serious way at least 1 time with nearly every fish type possible, it suggests that there is more at play here.

Perhaps it’s a variable not captured in the survey, like the order in which the wrasse was added–but what about the shots on goal theory–would we expect to have more issues with aggression and incompatibility with a higher number of fish interactions?

It’s likely no surprise that larger fish tanks have more fish in them.

But owners of larger tanks not only have more fish, they also reported more incompatible types, on average, than smaller tank owners.

Check out the data:

It was already established that there were not many people in the survey who had a tank < 20 gallons, but when we divide the total number of fish types listed as incompatible by the total number of aquarium owners with a specific tank size in the survey, another clear trend emerges.

Those people with larger tanks experienced a higher average number of incompatible fish types, giving more weight to the ‘shots on goal’ strategy.

That conclusion runs a bit contrary to some traditional advice in this hobby that larger tank sizes result in more territory to split up, and therefore less expected issues.

who took the survey It turns out, that people who reported compatibility issues in larger tanks, also listed a larger # of fish types that were incompatible with their 6 lines. So, perhaps it’s less about the size of the territory and more about the number of potential fish combinations and the order of those combination.

Conclusions about compatibility

When we look at the full body of data on the 6 line, a s

Smaller and shy fish like the marine betta, fairy wrasses, firefish, Royal gramma fish, or leopard wrasses won’t make good tank mates, as they run the risk of constantly being harassed by the six-line wrasse.

Also, while not a significant finding from the research conducted here, I still do advise against keeping this fish with slow swimmers like mandarin gobies, seahorses, and pipefish. The docile nature of these great fish make them likely to starve in their presence of an aggressive-eater like this, regardless of whether or not there are specific aggression/incompatibility issues..

Another aspect not explored in this research was whether or not the order in which the wrasse was introduced into the tank had an impact on compatibility.

In other studies, it has already been established that the order in which a fish is added to the tank does impact the relative aggression. The incumbent fish in a territory is more likely to fight to defend its territory from an interloper than the interloper is likely to challenge the incumbent to take away their territory or resources.

As such, if you are inclined to add a six stripe to your tank, consider adding it to a tank without a lot of other fish, and add them last.

The Six Line Wrasse - Pseudocheilinus hexataenia

Are six line wrasses jumpers?

There is some risk that a six-line wrasse will jump out of the tank when startled if you do not have a tight-fitting lid or another way to prevent the jump.

Pros and cons to consider before adding a 6 line wrasse to your tank

These fish are extremely popular, but like any good decision, there are some pros and cons you should consider before adding them to your tank.

six line wrasse close up eye

5 reasons to keep them

  • Beautiful
  • Inexpensive
  • Hardy
  • Will eat parasitic pyramid snails, flatworms, and bristle worms
  • Can be kept in reasonably small tanks (about 20-30 gallons or so)

2 reasons not to keep them

  • Can be aggressive fish
  • May out-compete shy fish for food

Six-Line Wrasse recommendations

There is no doubt, this is a gorgeous, hardy, and inexpensive fish–but the big question is whether or not you should add one to your reef tank. In a survey of 89 Six-Line Wrasse owners, 66% recommended them (as indicated by a score of 4 or 5 out of 5), while 11% did not (a score of 1 or 2 out of 5).

Sentiment towards the Six-Line Wrasse from owners skews positive, but the neutral-to-low distribution among 34% of respondents likely reflects the sometimes unpredictable behavior.

For more information

Check out this short video to learn more about the six line wrasse:

Here are a few other articles about semi-aggressive saltwater fish similar to the six line wrasse:

Or perhaps you would rather check out these other peaceful, hardy fish instead:

Conclusions

A lot of data were revealed here about the true intereactions between the semi-aggressive Six Line Wrasse and its fellow aquarium tankmates. Until now, it was unclear whether to trust the people who cursed the name due to compatibility issues they suffered or the people who raved about the brilliance of these fish.

As is often the case in life, both situations were likely true and accurate. It turns out that the is fish has a record of being a fine, trustworthy reef tank companion the majority of the time. About 4 in 5 reports indicate they were completely reef safe.

However, only 3 in 5 recommend the fish to others.

The next time you see this fish at your favorite local or online fish store, the data in this study should help you make an informed decision about what you can expect if you add one to your tank.

Six line wrasse aquarium care guide

References:

Saltwater Aquarium Blog Survey Data, October 2021

Comments

  1. Love my six line wrasse! He darts all over the tank all day and never seems to bother any of the clownfish, cardinals or shrimp that he shares a tank with.
    He’s beautifully and keeps to himself, perfect fish

    1. Author

      Hi Bobbie, thanks for sharing your individual experience with keeping the 6 line wrasse. It is a helpful reminder that there are no absolutes in this hobby. We’re dealing with animals and dynamic living systems. Individual results will vary. Definitely appreciate your contribution here.

      Regards,
      Al

  2. This is a great article. I have had a 6-line for many years and this fish is wonderful. (and a photo bomber) I have the wrasse with a firefish and also mandarin, but I also cultivate my own coepods and that is critical, as they will diminish the coepods for the mandarin. While the 6-line will eat other foods, most mandarins don’t. My first mandarin lived a very long time and would eat bloodworms right from my pipet. I haven’t had such luck with my second mandarin. He only goes for the live coepods…so I began cultivating them for him. He is worth it. I think the key is to have enough of their primary food source so they don’t need to pick on their tank mates.

    Thanks,
    Pam

    1. Author

      Hi Pam,

      Thanks for the great comment and for sharing your experiences with the 6-line and the Mandarin. Sounds like the 6 line is very well behaved. How do you culture the copepods? that sounds interesting and helpful?

      1. I cultivate the coepods and live plankton in separate 3 gallon drink dispensers I purchased on Amazon. I have piped aeration to both. I learned all the tips on how to set this up from videos on YouTube and reef blogs.

  3. My Six Line recently nipped at an upside down snail who apparently then snapped shut trapping my wrasses top lip/jaw. I discovered my Six Line struggling to release himself from the snails grip. I tried everything to get the snail to open up and let go. Eventually my Wrasse was freed but he is now missing his top lip/jaw. He seems to be doing fine so far though he seems to have some trouble eating with his unfortunately revised mouth. Will his mouth heal? Is there anything I need to or can do to assist him? I have been trying to figure out what I should feed him to make it easier for him to eat as he can no longer pick his food out of the water like he used to. Any help or advice would be greatly appreciated. Thank you, Pam

    1. Author

      Hi Pam,

      So sorry to hear about your Six Line + snail trouble. Got stuck in the cookie jar. Regarding the lip/mouth/jaw, it’s hard to say. I have never experienced this, specifically, but have seen minor mouth injuries heal on otherwise healthy fish. I have also seen more problematic injuries not heal. Are you able to remove the fish to a hospital tank to ensure you can adequately feed and keep the wrasse out of harms’ way?

      1. Hi Al,
        Thanks for the reply. My little Six Line was doing well in spite of his injury and I had just gotten some meds and food to try to nurse him through recovery when I found him dead in the tank. I had really hoped he would make it as he lived a few weeks post injury. He was an incredibly entertaining little guy!
        Pam

  4. My six line won’t let me have a lawnmower blennie. He will not let them eat,so they starve.

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