Your starry blenny is a combtooth blenny the same as a lawnmower so it should eat most green filamentous algae. As Karin said shortening it to under an inch if not 1/2 inch usually makes it more appealing I have found. Also I have found what helps a lot is that you reduce tank feedings by a good portion, until it seems to be under control, it seems to help. My thoughts are it has a 2 fold effect.

1) helps to limit its growth by lack of nutrients

2) The fish whom are natural foragers and have done so previously to survive in the wild will no longer be getting food dropped in from above. This means they go hungry and will revert back to what they know and that is foraging for their natural food, in this case filamentous algae.