That is a scooter blenny... but it is not a true blenny. Scooter Blenny's are actually Dragonets. Dragonet's are difficult to keep because they typically do not take prepared foods. They will feed on the pod population of the tank but not all tanks have a pod population that will support them so they often end up staving to death. The scooter is one of the easier Dragonets to convert to prepared foods but you need to watch him closely to be sure it is eating.
How old is your tank?? How much live rock do you have??