Live pond food, supplement or staple?

I have a healthy population of Gamarus shrimp and water slaters in my outdoor pond. The shrimp have been there for years, the slaters are new this year, probably from a new plant. To what extent will this be a food source for my 3 koi? I’m not feeding over winter, and it seems like the population is growing, presumably as the fish aren’t eating much. Will the fish help themselves to live food as they feel like it, or is it not of much interest to them? Mine are never very enthusiastic about pellet feeding, but seem to get on alright.