Arthur fetched this Barred Hamlet from around the boat in a depth of about 3m when we were anchored at Cayo Levantado- it was flapping around and swimming in circles, obviously either injured or stunned in some way. It was about 3 inches long. He seemed to recover a bit in a tub on the boat, so we returned him to the sea; Arthur says he waved his fin at us in a gesture goodbye!
Hamlets tend to stay in deeper water, using reef structures for protection- ours was obviously injured to be swimming alone by the surface over an area of sand. They have distinctive colouring, including a dark V-shape on the mid-body, and small blue dots on the snout. They can switch between male and female roles when spawning. They take advantage of the feeding habits of parrotfish, and are a predatory species, preying on fish and crustaceans.