I had a sleeper banded goby and it devoured hair algae. I had it initially for the sand and while it did an incredible job keeping my sand clean, it would actually rise up while sift the sand and get it all over the rocks and any clam or coral on the bottom or down low. I eventually got rid of it because of this. I had a HA outbreak a few years back and I noticed this goby would literally rip mouthfulls off of the rocks and and chow down like it was a buffet. It was also a model citizen and did not bother any other fish I had in the tank.
Here is a link to one: Saltwater Aquarium Fish for Marine Aquariums: Sleeper Banded Goby
Here is a link to one: Saltwater Aquarium Fish for Marine Aquariums: Sleeper Banded Goby