dmbutler47, That is a tough question that gets just a bit complicated.
First, I would judge a "keeper" by the size of the fish in the water you are fishing. It doesn't really take too long to figure out what the general size of the panfish are in a small body of water. Once I know that, then I try to stay in the upper ranges of size.
If a small pond or lake holds "bull" gills I return ALL the biggest males.
I have also fished 100 to 200 acre lakes that were over run with plump footballed 6 1/2 gills. In that case I took a cooler full and kept the eletric knife working for a bit to create fish chips.lol
I guess it's my opinion that it's really up to you! If I recall correctly, before I hit the reply button, it showed you being from Arkansas. I would think that that far south, I'd be looking for 8" + gills for "eaters" and straight up the scale for "braggers" :D Mike