The Three-ribbon wrasse (Stethojulis strigiventer) is also known as the Silverstreak wrasse, Silverbelly wrasse, Lined rainbowfish and Silver-streaked rainbowfish.
They are fairly common inhabitants of the reef tops in Tanzania and closely resemble the Blue-Lined Wrasse ( Stethojulis albovittata ) and the Cut-ribbon Wrasse (Stethojulis interrupta) which are all found in Tanzanian waters. Research on their mitochondrial DNA indicates that they are closely related to the parajulis and halichoeres genera.
The adult female or initial phase as seen below has an elongated silver body with a diamond pattern across the upper body. The lower body has a series of black lines across it, The face has black dots on it and under the eye is a short blue line. In the caudal area there are a series of alternating black and blue marks. The eyes are ringed in silver.
The terminal stage males as seen below from whom the species receive their common name are attractive looking fish. The lower body is a light white colour and the mid body is yellow, changing to an olive brown on the upper body. Behind the eye mid body is a black patch and below this separated by the shorter line is a red patch. The black patch starts as a small dot on the males and as they mature grows larger. The scales on the belly immediately behind the gills have a crosshatched pattern which changes a bit further back to a different angle.
The body technically has four blue lines across it, with the one below the eye being short and not going the full distance across the body. The second line from the top goes across the top of the eyes which are ringed in red. They grow up to 15 cm in length.
THREE-RIBBON WRASSE IN THE WILD
The Three-ribbon wrasse is fairly common on Tanzanian reefs between 10 and 18 meters. They are usually found in mixed rubble/ reef areas. The females are usually in groups of four to seven and often feed with other wrasse and parrotfish species and goatfish. Sometimes they are accompanied by a male and sometimes they are not. Males have several harems in an area and switch from harem to harem.
They are quick to hide and if threatened will bury themselves in the sand. The males are very active and patrol the reef at quite high speeds. There are a lot less males than females and from personal observations each male seems to have a fairly large territory with several groups of females in it. They are always on the move and hardly seem to stop and are constantly feeding. The are one of the more difficult wrasse to photograph.
The Three-ribbon wrasse is found on the East African coast from Algoa Bay up to the Red Sea across to southern Japan and the Marshall and Tuamoto Islands and down to New South Wales having a relatively large range. They are mainly seen on unprotected reef tops and rubble areas. They seem more common around the 12 to 15 meter range in Tanzania.
The Three-ribbon wrasse feeds on small crustaceans and mollusks. They scour the substrate and pick these off. They occasionally feed on their own but will usually follow a shoal of parrotfish, goatfish and other wrasse species feeding across the reef.
The males retain a harem and have several groups of females in their territories. Distinct pairing takes place.
The Three-ribbon wrasse are sometimes kept in aquariums but are not that well known and are suitable for professionals only. A large tank with plenty of copepods and zooplankton and suitable tank mates would be necessary and it may be difficult to wean them onto prepared foods. They would also require plenty of swimming room and a thick base of sand to burrow into at night. They will jump so the top should be secured. Fish from this genus are very difficult to maintain long term and require several feeds per day. They are almost certainly best left in the ocean.