The Blue Tang, also known as the Palette Surgeonfish, Blue Surgeonfish, Palette Tang, Palette Surgeon, Blue Hippo Tang, Regal Tang, or (by kids everywhere) as Dory, is a very popular salt-water aquarium fish. They may sometimes be seen cruising Indo-Pacific reefs in loosely coordinated schools, bottom-feeding on zooplankton and algae. When approached too closely they dive into the branches of nearby corals. 

The family Acanthuridae includes tangs, surgeonfish and unicornfish. "Surgeon" in the family name refers to the spine on the both sides of the caudal peduncle (between the end of the anal fin and the base of the caudal fin), shown here in the streamlined position at the front of the yellow portion of the tail. When the caudal fin is bent, such as during an attack by a predator, the sharp spine is exposed. 

Identification: Paracanthurus hepatus


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