Introducing; The HAMLET Family of Cozumel Island, México.
BUTTER HAMLET (Hypoplectrus unicolos)
This subspecie is found nearly in every reef of the Island now days as always, the lower dorsal fin when display is bright yellow, and goes well with the butterish color of the rest of it's body, notice the black saddle like spot on base of tail, the blue markins around the eyes and the black spot on it's nose.
Great to caption on a close up, try it.