I have a goldfish that hasn't seemed very lively for a week or so and today I can see a long white thin thread trailing from his body, and some of the white scales look funny when viewing him from the top. I haven't caught him to look at him closer since I don't want to stress him.
Any ideas what this is? Parasites? How should I best treat him? I have two other goldfish in my little half barrel pond as well.
Thanks in advance,