Way too small for any tang, an algae eater you could choose is an lawnmower blenny but they can be fiesty and will limit other choices and may also run out of food. Best bet - don't have algae - too simple eh??? - no I'm not being sarcastic. Hair algaes will not grow in a clean system with proper light (quanity and spectrum) or on rock that has a good coraline algae growth. I have no algae in any of the tanks I am currently running, hair algae is a symptom of a problem it is not a given. And if some of your rock grows macros - cool - you can simply prune it by hand.