Thalassoma lunare  

Thalassoma wrasses comprise several cigar-shaped, fast swimming, robust and to a degree aggressive fishes of good to okay to poor aquarium use. The larger species when shipped of size and from far away (long times in the bag) suffer especially. Most species stop growing at about six inches, though a few about double that in the wild. Like most wrasses they are good with only one male to a tank, and need soft sand to dig and sleep in. Thalassoma lunare (Linnaeus 1758), the Moon Wrasse (2), sometimes comes in great, other times... all die. Red Sea and Indian Ocean,  to the Line Islands. Length to ten inches.. 

Photo by Mike Iannibeli - text with permission from Wetwebmedia