As long as the poop doesn't look stringy or white then I shouldn't worry. And make sure that it's solid. I don't mean to touch it or anything, but just keep a eye on it. Just to be on the safe side, don't keep on cleaning the tank though. This could be proven to be annoying... For the fish, otherwise they might want to die! But seeing as you have had them for 8 years, they could die soon, as a life span of a goldfish is 3 yrs... My dad though, he had a goldfish for 28 years! And that was from a fayre!
