I have a 500 gal. pond, add water and conditioner as needed, use CalPump with filter to keep water oxygenated and clean. While I have been scooping leaves from the bottom during the last couple of months, usually with a few days between each scooping to give the water time to clear again, I have not made any major changes to the environment and all other fish seem fine.  I have 8 large Shebunkin (5"-9") and two small ones born in the pond last year.  Most of the fish are more than a year old.  This weekend I did add water clarifier and algae remover but the problem occurred before this.

I have one fish with a white "pimple-looking" raised spot about 1/8" in diameter.  He has had it about a month.  I do not see any other symptoms of illness on any of the fish, but as a rank amateur, I might be missing something.  No ragged fins, no cluster of small white spots, no eye symptoms that I can see, however.  Here is a photo taken today.  It is the fish near the top.  I have a net due to heron problems.  Not a great photo but expedient.

Could you please help?  Thanks

Thanks. I downgraded the res on the photo so much it's not clear. It looks exactly like an acne pimple although more irregular in shape.  It's about 1/8" in diameter.  Louise

Thanks.  Since the last post, the spot opened
and floated like a worm attached to the fish.  Then,
after a few days, it broke off and there is no apparent
wound remaining on the fish. All the fish are active,
appear healthy, and many are laying eggs.

Thanks

Thanks. I didn't know fish got cysts.  Glad to know this forum exists.  Appreciate your time.  Louise