i have had this scooter blenny or scooter dragonet for the past few months. He is my fav fish i have in the tank. He scoots around picking off the live rock and picking up sand and spittng it out. He changes his colors when he goes from the rock to the sand. when he is on the rocks he is brown with lime green and white spots and sometimes a lite purple, but when he is on the sand he is more of a white with lime green and light brown spots. He is only 2 inches long and i think he is a she cuz of that first fin on the top of him(not sure the name of it), its small and i think the males have a larger one of these fins. Is it common for them to change color like that?