They look like BG from any native BOW in this area. I think that if you feed 'em a good food, they will get larger. I think the limiting thing in the pond is food for them.

If not feeding, removing a bunch will leave more food for the rest, but that will be detrimental to your LMB population.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).