Kycatfishing

I have a 1 one acre lake a little bigger than a football field and it's about 30-40 years old and about 5-6 foot deep with a deep spot of 7-8 foot max. One time the lake flooded over and I went noodling for fish in its little flood creek I caught about a 100 gizzard shad over 6 inches and a huge ass goldfish. In the lake itself there crappie bass bluegill sunfish minnows shad channel catfish flathead blue and bullheads and car The bass get a max of about 7 pounds. We put 1 flathead 18 pounds a year ago and about 4 blue over 20 including a 38 pounder. The channels get about 20 pounds max from what we've caught. The bluegill are hand sized. And over time when we go noodling we caught 6 carp around the 10 pound range and a 12 pound flatty and a 6-8 pound blue that we never put in ???? Which confusses me? There's also 30 pound snapper turtles and 80-100 pound monster beavers on the little lake . So my questions are why are there smaller blue in the lake?? Why are the shad do big??? How do I get rid of the flattys and bullhead ??? How big will the blues get??? There's about 2 foot of silt on the bottom will catfish use this ?? And is this a good Eco system there's also huge bullfrogs and crawdads pleassssssereeree help me