Long time lurker and minimal poster BUT any suggestions on how to increase the size of my bream in my pond, loads and loads of little fish less than 3" occasionally catch a 5-7" fish but I'd like to increase the size on the majority of the fish instead of a gazillion little bait stealing thieves

Pond info, about 1/2 acre, mostly 4-6' with a deep end 12' and spring fed, also, it is an existing pond on property we bought (future homesite) a few years back, I have made a few improvements and I am trying to get it "cleaned" back up a little, weeds and algae included, so the grandkids will enjoy it more, thanks for any and all help