Paracanthurus hepatus, commonly known as the regal tang(sometimes calle Dory), is an average-sized colorful reef fish belonging to the family Acanthuridae. A popular fish in marine aquaria, it is the only member of the genus Paracanthurus. A number of common names has been attributed to the species, including but not limited to palette surgeonfish, blue tang, hippo tang, flagtail surgeonfish and the blue surgeonfish.