A quiet corner of the internet about fancy goldfish, tank water, and patience.
Welcome. This page has been mostly neglected for a while, but I've been keeping fancy goldfish for a few years now and I figured I'd jot down what I've learned so the next person Googling at midnight because their ryukin is upside down can skip some of the dead ends.
Nothing exotic. Two fantails, one oranda (named Biscuit), and a ryukin that I'm pretty sure was sold to me as a fantail. They live in a 55 gallon tank with a sponge filter and a canister. Everyone gets along. Biscuit is the messiest and also the most dramatic :: he wedges himself behind the heater and then panics.
I feed a soaked sinking pellet in the morning and a small portion of defrosted bloodworms or thawed peas in the evening. Peas help with swim bladder issues in fantails. Biscuit would eat until he exploded if allowed, so he's on a strict schedule.
My tap water is on the hard side, around 220 ppm TDS. I don't bother with RO; goldfish are actually happier in slightly hard water. I dechlorinate, let it sit in a bucket overnight to warm to room temperature, and siphon it in slowly. If you're on a chloramine system, a conditioner that handles both chlorine and chloramine is worth the extra couple of dollars.
The only serious illness I've dealt with was flukes, brought in on a plant from a pet store. Salt baths at 0.3% for ten minutes worked for two of the three fish. Prazi dosed in the main tank cleared the third. Quarantine new anything, even a piece of driftwood, for at least two weeks.
I don't update this often. When I do it's usually because something went wrong and I want to remember it next time. If you're reading this and you're stressed about a fish, take a deep breath, test your water, and do a 25% change with temperature-matched dechlorinated water. That solves more than half of everything.