Green hair algae

[naesco]

Take a look at the size of the guys tank before recommending a tang.

The regal is omnivorous. It is the only tang that is a meat eater.
If you saw it in algae it was searching for meatly morsels in the algae.
Simply put the yellow and regal tang are not good options.

A sea hare is a good option if you take the time to acclimatize it and feed it algae or return it to the lfs when the algae is done.
Don't let it starve in your tank.

The best option is to clean up your water problem and you will find that the algae problem will go away over time.