make sure its a watchman goby. they are the ones that form relationships with pistol shrimp. some watchmen are yellow, daimond back, and other ones. i cant name them off the top of my head.
yellwo watchman,pink spotted watchman, Hi fin goby, orange spotted,steinitz goby,orange strip spawn,blue spotted, wheelers,pinkbar,yashia white ray,luther's watchman.
all shrimp gobys for ya.