There is nothing more disconcerting to a diver than when you are swimming along quite happy  then you look around and you have a school of fish following you~! This has happened to me a number of times. Well I turned the tables on this shoal of Tuna as I had my camera with me at about 20 feet over coral reefs in the Caribbean sea. They did not seem put off by the flash and kept following me& they had a hungry look on their faces&.......