For the untrained eye, it appears the swans are feeding the fish intentionally. However, it is an inadvertent feefing. Swans must have water to feed to prevent choking. The swans grab food in their beaks and immediately dip it in the water to swallow. In doing so, food drops out of their mouths and the fish readily appear to eat the dropped morsels. All swans exhibit this behavior, but some may chase the fish if they get too close. The Regal Swan