You seldom think about corals catching and eating your otherwise healthy fish but it might be good to know that it does happen. You might want to avoid coral species such as Trachyphyllia and other large polyp stone corals in tanks where you keep fish you really care about. The risk of something like this happening is small but ever present.
The video below shows an open brain coral in the tank of Dmitry Tumanovthat has caught and is consuming an otherwise healthy, living, large azure damsel fish. Dimitry shot this video after having lost several fish that was no where to be found.