It is believed that the Watchman Goby changes color when they change sexes. In the wild the largest of the Watchman Gobies undergo this change. Pictured above is my Watchman Goby a year after I got him. Last year he starting becoming paler and started to develop distinct bars around his body. The pictures below was taken today. This Yellow Watchman Goby has been in my reef tank for three years and is a very personable fish.
