REEF2REEF Saltwater and Reef Aquarium Forum
This may be a tough one as they both compete for the same algae on the rocks, although, this is the first time I have heard of a conflict between these 2.
I would recommend putting a mirror on one end of the tank as this should keep the tang occupied for a while, unleashing his aggressions on "another tang" vs the blenny.
leave it there for a day or 2 and then remove and see if that helps.
I'm also tagging #eatbreakfast for any advice........be sure to follow it if he has some to offer on this case!
good luck......they are both great fish.