I noticed a couple of black grubs on the anal fin of this one. None of the others had any. All looked healthy, which is great because last spring was a bad one for fish losses, but that is another story for a different thread.
Corgi, depending where you are, add Redear Sunfish or Pumpkinseed Sunfish to your pond. They will eat the snails which is allowing the black spot to flourish.
