Difficulty: Moderate - Hard
Minimum tank size: Fancy (20 gallons per fish) Single tail (30 gallon pond or 10 gallons per inch of fish starting with a 30 gallon aquarium. THESE SHOULD BE POND FISH!)
Temperature: Cold water 50-77′f
Diet: Omnivore/ opportunistic scavenger
Lifespan: 10-40 years (Fancy goldfish tend to live shorter lives but can still often reach their 20′s without issues if cared for)
These fish are really pond fish. Fancies can be kept in tanks more easily requiring 20 gallons per fish. They’re social animals so should have at least one, and preferably 2 friends. So look into the 40 gallon to 60 gallon range for tanks. Filtration should be heavy but not strong. You want to look for a filter that is for double the tank size and have it cycled. They don’t require heaters and may even require a cooling system in the summer. Temperature variation is taken very well and has been known to be beneficial. You don’t need substrate and if you do use some slate or sand as best practice, they may eat and choke or become impacted on gravel. Algae and green water is very beneficial acting as plants in the tank and a grazing source.
Single tail goldfish grow massive! They’re really pond fish and should be treated as such. A standard 30 gallon pond form can house an adult common, comet or other single tail/long body variety. As you should have more I’d look into a 60-90 gallon form for a pair or trio of smaller ones. If you do house in tanks you want 10 gallons per inch of fish to allow for adiquite swimming space. If you plan to play size up start with no less than a 30 gallon, realize they will outgrow it fast. For an adult you’re looking at a 120-140 standard. You may be able to manage a pair in that. Custom tanks are good, you’re still looking at a big tank though! 3′x4′x18″ is the absolute minimum for a pair or maybe a trio in a custom. Out side of that all the same rules apply as with a fancy.
-Tank ranging from 30-120+ gallons
-Or a 30+ gallon pond form
-No heater required! May need a chiller if in hot climate and can’t keep cool.
-A filter rated for twice the size of the tank or pond
-Substrate not required, a thin layer of pool filter, play or aquarium sand can be used if you want. Slate is also an option.
-Decor and hides not super needed. You can use natural decor, attempt plants or have pvc pipe though.
-Lighting is optional, if you plan to grow plants or algae an appropriate sized lamp will be needed.
Other non optional supplies/perishables:
-A liquid master test kit (Nutrafin or api)
-A water conditioner (prime, safe, stress coat are good brands)
-A bucket and syphon that hasn’t been used for anything else (water changers are nice if you have ponds on the ground or big tanks)
-A log to help with cycling and recording things.
-A high quality sinking goldfish or koi pellet.
Goldfish are scavengers and will always accept food if healthy. Feeding should be regulated. You can feed up to 4 times a day with each feeding being about two mouthfuls. They won’t suffer if you only feed once or twice though. Watch for overfeeding especially with fancies, they have a poor digestive system.
Food staple should be a good high quality goldfish sinking pellet. Hikari has a good line. Omega one and new life spectrum also have good foods. Flakes are not appropriate. If floating pellets need to be used soak them so they sink before offering. You can supplement feedings with chopped frozen or blanched veggies, leafy greens, bits of fruit and frozen cubed foods. High fat diets are fine, they do best on a diet that is lower in protein though.
They really shouldn’t be kept with anything but other goldfish of the same type (Fancy or single tail) . Pleco are not good tank mates and will eat the slime coat off goldfish, algae is good for golds anyways. Cories with often end up in the gold fish’s mouth resulting in the death of both. All other catfish and pleco should be avoided. Actually just avoid all other fish, shrimp and snails. The only successful thing I’ve seen is full drown adult dojo/weather loaches with single tail golds. But even then, it’s not really worth it.
Single tails are prone to spine malformations, ich, velvet, flukes internal parisites and other external parasites, columnaris, and fungal infections. Most of these can be prevented by proper housing, diet and a quarantine period. Have melafix, pimafix, triple sulfa, fenbonazol, prazi and paragaurd on hand. It’s also good to have epsom salt and aquarium salt.
Fancies are prone to all the above as well as digestive issues, swim bladder disorder and eye damage/popping (often caused by the pop eye bacteria).
The above are two great sources you should give a read before you get a fish. Also show them your support!