David - thanks for the reply. No one knows what causes this exactly but as I'm sure you know, it's only temporarily. People think it's either from toxins ...more introduced into the water or from fish being handled previously and released. I lived in Missouri and used to fish a deep quarry that's stayed cool throughout the summer and had smallmouth. They would get black spots in the fall and there were always a ton of geese sitting in the water during migrations. Toxins introduced into water from goose poop causing this? That was my experience but who knows
That one came from the Susquehanna River near Harrisburg PA. About 1/2 of the bass have this blotchy bass syndrome, but most at not nearly this bad. This only happens ...more when the water is cold. None of the bass I catch in the summer have any black spots.