They are all opportunistic feeders. They will eat the easiest thing they can catch that offers the most positive energetic results. They will do that until the results are negative and then even keep eating less nutrient rich meals (losing weight however)until they starve to death.

The question is if you have a good pond (lots of well conditioned fish of all sizes) then how drastic of a change do you want to make (risk profile) and are there better (less drastic methods) that will get you to the same place with less risk.