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
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.
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.
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.