The Saddle Wrasse, Thalassoma duperreyi, has two phases of coloration it goes through. The first phase is a blue/grey color with a dark blue head, purple accents on the dorsal and caudal fins, and a thick yellow "saddle" across its back. The secondary or terminal phase being males - females that have changed into males - are a dark blue-green. The juvenile coloration is uniformly darker on top and lighter on the bottom.
The Saddle Wrasse should be kept in a tank with plenty of live rock for hiding places, and a thick sandy substrate to allow burrowing, as well as a tight lid to prevent escapes. This Wrasse is extremely active during the day and will sleep deep in crevices during the night. Though they are peaceful as juveniles, and will even clean other fish they tend to become more aggressive as adults and should be kept with similar sized and semi-aggressive tank mates. They will also become aggressive towards other Wrasses as adults.