In case of danger, they raise those blades to wound their assailants. The blue tang lives in coral reefs. It prefers areas with active currents and so can be found nearby the reefs' outer slopes and channels, at 2 to 40 m below surface.
The fish form into scattered groups that swim a few metres above the reefs. If they feel any danger, they hide amongst the branched coral. This is a diurnal fish that feeds on zooplankton and the microalgae that it scrapes off of rocks.
It would appear that groups of blue tang are made of one male and several smaller females.
Slight differences in colour can be seen, depending on the geographic origin of the fish. For example, the belly is slightly yellowish in specimens from the Southern Indian Ocean.
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