Well if you mean a Lawnmower blenny yea im sure theyll eat any type of GOOD algae like the green one, if you ever run out of algae just place algae sheets in the tank and thatll be good
I tried one when I had a hair algae outbreak, he wouldn't even look at it. Just my experience, maybe you'll find one that has an appetite for it, because I think they are supposed to like it.