That poop is neither white or stringy. It looks very full and healthy, just in huge portion! I have had fish with internal parasites and it does NOT look like that at all. You would see sections of the poop that were totally clear and the only reason you could tell it was there was there was some solid poop attached to both ends. Im almost positive your fish is fine, just being a goldfish
If it were constipated it wouldnt be pooping..read up on it. it could be constipation, a bacterial infection, or internal parasites. if you think its constipation dont feed for three days and then feed some green peas.
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