As juveniles some Thalassoma wrasses perform cleaning services for other fish, eating parasites off their bodies!…though they are not so inclined when they grow up!

Thalassoma Wrasses are beautiful and intriguing fish with a most distinctive manner of swimming, they use their side fins similar to that of a bird flapping it’s wings. You’ll find their common names often describe their attractive or unusual characteristics. Their body shape is often likened to a cigar or a banana and their exceptional coloration brings up images of sunsets, rainbows, peacocks, lollipops, and even the moon!

Graceful and very colorful, Thalassoma Wrasses are very active, fast swimming fish. They are bold and hardy, an excellent inhabitant for the right marine aquarium and can live for many years. There are three main traits to consider for keep these fish: they are rather large fish and need a good sized aquarium, they are rather aggressive, and though they don’t eat corals they will eat crustaceans, invertebrates, and other small fish.

For more Information on keeping marine fish see:
Guide to a Happy, Healthy Marine Aquarium

Bluehead Wrasse, Thalassoma bifasciatum in the wild
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Male Blue Headed Wrasse attracting females.

This male Blue Headed Wrasse is trying to attract the yellow females below him. This is one of the FEW Thalassoma wrasses that work in a reef. They get to be about 6″ and love to swim! They are great at getting rid of larger Bristle Worms and may eat small hermit crabs once they get older, but will not bother corals.

Blueheaded Wrasse, Thalassoma bifasciatum in captivity
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Blue Headed Wrasse in a 100 gallon saltwater aquarium

Typical behavior of a Blue Headed Wrasse (Thalassoma bifasciatum). They only grow to 6″ in length, and work great in reef settings that need the Bristle Worm population taken down! Unlike Coral Shrimp, they don’t completely decimate the populations by eating the eggs, rather they only eat the larger creepy crawlies.

Cortez Rainbow Wrasse, Thalassoma lucasanum
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Cortez Rainbow Wrasses group in the wild with males, juveniles, and females

The handsome male Cortez Rainbow Wrasses have 3 bright colors, while the pretty juveniles and females have a red tail and are black and yellow striped! They only grow to around 6″ and are a great addition to your reef tank. They will pick off Bristle Worms and small hermit crabs and very small snails, but will not bother corals.

Saddle Wrasse adult, Thalassoma duperrey
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A Kona snorkel trip shows a great display of the Saddle Wrasse in their natural habitat.

The Saddle Wrasses are very handsome fish that grow to about 6-7″ in length. They are definitely one of the Thalassoma wrasses that will hold their own with most other fish! They do well in a reef, but will eat small crustaceans, molluscs, ornamental shrimp, and then very small fish once they are full grown. Yet their ability to get rid of pests such as bristleworms makes them quite valuable in a “predatory reef” set up.

Sixbar Wrasse, Thalassoma hardwick
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Male Sixbar Wrasse in the wild, also called Hardewick’s Wrasse.

Great illustration of how a Sixbar Wrasse, or Hardewick’s Wrasse, behaves in the wild. These wrasses are very colorful with the males being the brighter sex. They can hold their own with most other fish and do fine in a more aggressive or predator type reef tank. They will reach up to 6-7″ and once they are full grown any small slender fish, like dartfish. will be in danger. These fish are constantly swimming, thus leading to a big appetite and should be fed several times a day. They will rid your tank of unwanted bristleworms, but will also eat other small invertebrates, including sea stars.

Yellow-Brown Wrasse, Thalassoma lutescens
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A lively Yellow-Brown Wrasse male, sometimes mistakenly called the the “sunset wrasse”

The Yellow-Brown Wrasses, Thalassoma lutescens, is lively in action and in color! It has acquired many names due to the different color forms that appear between the juvenile phase and adult phase. Some mistakenly call them a Sunset Wrasse, but the true Sunset Wrasse Thalassoma grammaticum does not have a blue collar. They are easy to maintain but will reach almost 12″ in length, so will need a large tank to swim in during the day with rock work to hide among at night.

Thalassoma Species

   The Thalassoma genus is comprised of about 27 known species. They are members of the wrasse family Labridae, in the subfamily Corinae. Wrasses comprise a huge family of fish that are surpassed in species diversity only by the Gobidae (gobies) family.
   Thalassoma wrasses are quite ancient, estimated to have originally diverged 8 – 13 million years ago with the ancestral species being the Blacktail Wrasse Thalassoma ballieui and the Seven-banded Wrasse Thalassoma septemfasciata*. The Ornate Wrasse Thalassoma pavo was the first species described, by Linnaeus in 1758.

   *Reference: Bernardi, G.; Bucciarelli, G.; Costagliola, D.; Robertson, D. R.; and Heiser, J.B., Evolution of coral reef fish Thalassoma spp. (Labridae). 1. Molecular phylogeny and biogeography, Marine biology, Vol.144, No. 2, (pp. 369-375), 2004.

Habitat: Natural Geographic Distribution:

   Thalassoma wrasses occur in tropical and subtropical waters worldwide, predominantly on coral and rocky reefs. Being diurnal (active during the day), they are primarily seen nimbly swimming and foraging above shallow tropical reefs. They also like deep sandy bottoms where they will burrow when extremely frightened. They may sleep on the sand bed or will retire into the reef, resting on coral branches or in nooks and crannies.


   None of the Thalassoma species are listed in the IUNC Red List except for one. The Greenfish, Thalassoma ascensionis, is listed in the IUNC Red List as Vulnerable due to the low number of naturally occurring species in the wild.


   The Thalassoma wrasses are elongated streamlined fish, often described as being ‘cigar’ shaped. Many are quite colorful, even exotic looking. They range between 3.9 inches (10 cm) for the smallest, the Greenfish T. ascensionis, and reach up to 18 inches (46 cm) for the largest, the Surge Wrasse T. purpureum.
   Some features they have in common with all wrasse species, especially noteworthy is a protractile mouth with strong lips and protruding pointed front teeth. This allows them to reach foods from a variety of areas and then they can use their pharyngeal teeth for crushing the tough foods.


    Thalassoma wrasses are ‘carnivores‘. They feed primarily on benthic foods as well as zooplankton in the water column. Depending on the species, diets include all sorts of crustacea and invertebrates, small fishes, and foraminiferans. Juveniles of some species, such as the Cortez Rainbow Wrasse T. lucasanum, will clean parasites off of other fish.
   Having very hearty appetites, they are easily trained to eat prepared foods in the aquarium. Thalassoma wrasses should be fed a varied protein diet strong in small crustacea, also frozen foods such as mysis and brineshrimp, and even flake foods.

Maintenance Difficulty:

   Thalassoma wrasses have a great history of easily adapting to the captive environment. Once acclimated they are known for being quite hardy and long lived. Though they will not bother corals, Thalassoma wrasses eat invertebrates and crustaceans, so are best kept in a fish only aquarium. They are also good sized fish and need lots of room. As adults they become more aggressive, even snacking on smaller fish, so tank mates need to be other large somewhat aggressive fish. They need a good sized aquarium with a sandy area on the bottom and lots of rocks providing nooks and crannies.
   Their biggest challenge, especially for the larger specimens, is in shipping. The long distances traveled, means long periods of time in shipping containers, which is quite stressful. Getting these wrasses settled into their permanent home as quickly as possible is of primary importance.

Social Behavior:

   In their natural habitat Thalassoma wrasses are usually seen in harems. The harem consists of one dominant male nervously swimming about, guarding several juveniles and large females to inhibit females from turning male and taking over the harem.
   Juveniles also have some interesting behaviors. Some juveniles, such as the Bluehead WrasseT. bifasciatum and the Bluntheaded wrasse T. amblycephlum, associate with stinging anemones for protection. Juveniles such as the Cortez Rainbow Wrasse will act as cleaners, removing parasites from other fish. Though as adults they become more aggressive, no longer inclined to act as cleaners for their tank mates. Despite their social behaviors in the wild, in the aquarium they are best kept singly (or possibly in a male/female pair in a 125 gallon) , sharing the aquarium with other more aggressive natured large fish.


     Though they are diurnal, sleeping at night, Thalassoma wrasses are quite active during the day, nimbly foraging for foods and darting through corals and rockwork. They swim using only their side pectoral fins unless a burst of speed is required, then they use their caudal fin. They will sometimes bury themselves in the sand substrate if extremely frightened and very active species will take occasional rest periods, laying on top the sand bed.

Breeding / Reproduction:

    Like all wrasses they are protogynous hermaphrodites, meaning that most of these fish are born female, and become male if necessary. For many of the wrasse species, the sex change will be triggered if the opposite sex is absent, then the largest female will change to male. However the Thalassoma wrasses are a bit different, for them there needs to be visual clues from a smaller conspecific. And, these must be behavioral clues rather than being the color or sex of the other fish.
   They spawn year round during the daytime (as they sleep at night), though time of day is unimportant. Wrasses will spawn in one of two ways, sometimes as an entire group but more often as a pair where the dominant male spawns with each female individually. The pair will perform a courtship dance, so-called looping, where the male will spread wide his fins and flaunt them in front of the female. The couple will then swim together to the surface, quickly spawn, and then dart back down to the protection of the reef.
   Breeding Thalassoma wrasses in captivity has not yet been reported successfully. This is most likely because of the large amount of space required for the courtship and spawning to occur.

Moon wrasse (Image Credit: Rickard Zerpe, Wikimedia Commons CC BY-SA 2.0 Generic)