Short answer, they will eat the from time to time. Sharks are well fed, and won't hunt for food. However, if a fish acts abnormal or does something to draw attention, the white tip reefs will single it out and go into their 'pack hunting' mentality. Once they start, the hormones in the water trigger that same behavior from all the sharks in the display.
I have specifically picked various grunt species as filler fish due to that. Grunts are hardy, cheap and very plentiful fish. They are also bite sized. Big fish when taken by sharks will get ripped up and they'll leave half bodies floating around which gets messy very fast. It's little stuff like that you learn over the years which leads to better long term shark displays.