What Size Tank Does a Common Goldfish Need?
Minimum tank: 40 gallons
A Common Goldfish (Carassius auratus) grows to about 10 in (25.4 cm), so the practical minimum is a 40-gallon aquarium. A pair or small group is typical, so leave a little extra room for tankmates.
| Single fish or pair | 40 gallons |
|---|---|
| Comfortable group | 40 gallons |
| Community setup | 50 gallons+ |
Bigger is easier: more water dilutes waste and holds temperature and pH steady. See stocking ideas for a 40-gallon tank or try the stocking calculator.
Frequently asked questions
What is the minimum tank size for a Common Goldfish?
At least 40 gallons.
Can a Common Goldfish live in a smaller tank?
Going under 40 gallons stresses the fish, worsens water quality and shortens its life — not recommended.
More on this species: Common Goldfish full care guide · tank size · temperature · pH & hardness · tank mates