My yellow Watchman Goby is exhibiting similar behavior, except he is at the top of the tank. We just added a Royal Gramma about two weeks ago. What can I do for him? Aside from the Gramma, there are two Clown Fish, and a green cromie. All of which are doing fine. The corals and invertebrates appear to be healthy as well. Our 35 gal tank is about 8 months old.