From the color of the fins, they're either Hybrid Bluegills or GSF, not straight BG. I think that "rash" could be due to spawning injuries, hot water, stress or a combination of all 3.

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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).