Yes! Goldfish do need a big tank – never keep goldfish in a bowl!
It’s important to realize that the goldfish you buy in your local pet shop are very young and have not reached their full size.
You might be surprised to know that common goldfish can reach up to 10″ and fancy goldfish can reach up to 8″, so you definitely need a big tank for them!
Recommended goldfish tank sizes:
Fancy goldfish: 3 feet long and a volume of at least 20 gallons for one goldfish. If you plan to keep more than one goldfish in your tank then add an extra 10 gallons for each additional fish.
Common goldfish: 4 feet long and a volume of at least 30 gallons. If you plan to keep more than one goldfish in your tank then add an extra 12 gallons for each additional fish.
It’s worth noting that common goldfish are often more suited to a pond once they grow larger in order to ensure that they have enough room to swim around. Very few people have an indoor aquarium large enough to properly keep a fully grown goldfish!
Finally, don’t forget that your goldfish tank needs a filter!
Even a big tank will get polluted very quickly if it isn’t properly filtered or if you don’t do enough water changes. If possible, get an external filter, as they have a larger volume than internal filters, and sit outside your tank so that they don’t take up valuable space inside your aquarium.