They are often found for sale at larger size, but you can also get them small.
Zebrasoma spp. tangs will eat hair algae as well as Siganus spp. The Fox Face.
Hermit crabs will eat it, but it depends on how much you have.
If you have one of those huge blooms, its worth to check the water parameters and find out why you have such a bloom and take care of the water parameters as well as the algae itself.