Most of these can also apply to the majority of tropical fish. Did you get these from an article? Did they also list treatments?
As with most fish, water quality should be pristine. All too often new hobbyists fall for the "goldfish in a bowl" marketing hype, or the dreaded "1 inch per gallon" rule, which really does not apply to golds. Because golds really have no stomachs, food passes through them much more quickly, and they release massive amounts of waste. The old saying, a oz of prevention is worth a pound of cure is perfect advice for golds. Keep fancies in 15-20 gal PER gold, and keep the commons and kois in ponds, not aquariums, and they'll live long and healthy lives.
