The Surgeonfish family includes about 80 species, including unicornfish. Many of the species are quite colorful, or otherwise distinctive - such as the unicorns. The distinctive characteristic of the family is the spines, one or more on either side of the tail, which are dangerously sharp.
Atlantic Blue Tang
Also called: Blue barber, blue doctor, blue tang
Scientific name: Acanthurus coeruleus
Sleek Unicornfish
Also called: Blacktongue Unicornfish
Scientific name: Naso hexacanthus
Unicornfish are a family of Surgeonfishes. Some, but not all, members of the family have a single "horn" on the forehead, giving the family its name. The Sleek Unicornfish is one of the larger members, and as the name implies, the body is a bit more streamlined that most stout-bodied Surgeonfish.
Razor Surgeonfish
Also called: Yeollowtail Surgeonfixh
Scientific name: Prionurus laticlavius
The Razor Surgeonfish is common in Mexican waters. The photograph was taken in the waters off La Paz near the southern-most tip of Baja California.
Powderblue Surgeonfish
Also called: Powder blue tang
Scientific name: Acanthurus leucosternon
The Blue Tang was quite common in the outer reefs of the Maldives, but I've also seen in around Komodo in Indonesia. Like the other Blue Tang, it was very difficult to photograph, that is, until the Mantas showed up. Then it seemed like it wouldn't get out of the picture.
Indo-Pacific Bluetang
Also called: Palette Surgeonfish, Regal tang
Scientific name: Paracanthurus hepatus
The Palette Surgeonfish is not common, but they sure stand out in the reef crowd. They are very hard to photograph. I got luck to find one on the upper reef feeding.
Blue-lined Surgeonfish
Scientific name: Acanthurus lineatus
The Blue-lined surgeonfish is a bit more solitary than other surgeonfish. In fact, it's reported to be quite territorial, although it can't do the damage to divers that triggers can do.