Goldfish care guide
Carassius auratus · Cyprinidae
Goldfish (Carassius auratus) is an aquarium animal. It belongs to the Cyprinidae family. It is native to Selectively bred for colour in China more than a thousand years ago (the Song dynasty already had yellow, orange, white and red-and-white forms); from the Ming dynasty it was also kept indoors, which allowed mutations that cannot survive in ponds to be selected.. Water temperature: Avoid below about 10 °C (fancy varieties) and above 30 °C. pH: 6.0 – 8.0. Care difficulty: Easy on water and food, but needs a bigger tank than people expect.
How do you care for Goldfish?
| Temperature | Avoid below about 10 °C (fancy varieties) and above 30 °C |
|---|---|
| pH | 6.0 – 8.0 |
| Placement | A coldwater fish that can live in an unheated tank. Wikipedia suggests about 76 litres (20 US gal) per common or comet and about 38 litres (10 US gal) per smaller fantail. |
| Growth | Common and comet types can reach about 41 cm; the longest reported is 48 cm. Fancy varieties stay smaller. |
| Difficulty | Easy on water and food, but needs a bigger tank than people expect |
| Family | Cyprinidae |
How do you trim and propagate Goldfish?
Breeding usually follows a significant temperature change, often in spring and mostly in ponds. Fancy varieties kept with single-tailed relatives can stunt or starve because they compete poorly for food.
What problems affect Goldfish?
Rapid temperature changes can kill, especially in small tanks; below about 10 °C is dangerous to fancy varieties and above 30 °C is also harmful.
How do you fix Goldfish problems?
Keep the temperature steady and match the temperature of new water when topping up.
Where does Goldfish come from?
Selectively bred for colour in China more than a thousand years ago (the Song dynasty already had yellow, orange, white and red-and-white forms); from the Ming dynasty it was also kept indoors, which allowed mutations that cannot survive in ponds to be selected.
What should you know before buying Goldfish?
Common and comet goldfish outgrow small tanks; abandoned fish in the wild have reached over 40 cm. Never release them.
Sources
- Goldfish — Wikipedia
- Carassius auratus — FishBase
Care details checked against these sources on 2026-10-29.
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