Tank

In this article, we look at goldfish water temperature and how the temperature of the water in your goldfish tank affects your fish.

We often hear about how goldfish are hardy fish that can survive a wide range of water conditions – including very cold and quite warm water – but are some temperatures more suitable for goldfish than others? How hot is too hot? How cold is too cold? And what temperature encourages goldfish to breed?

Read on to find out how best to measure your goldfish tank temperature, the right temperatures for breeding goldfish, non-breeding aquarium temperatures, and the importance of air supply in warm water.

[Read more…] about Goldfish tank temperature

Yes! Goldfish do need a big tank. You should never keep goldfish in a bowl. Instead, always make sure your goldfish tank size is appropriate to the current – and potential – size of your fish.

We talk about potential size because you don’t just have to give your goldfish enough room for today. You need to give them room to grow.

It’s important to realize that the goldfish you buy from a pet store are very young. They haven’t yet reached anything close to their full adult size.

You might be surprised to learn just how big goldfish grow.

Common goldfish can easily reach 10 inches and fancy goldfish regularly reach 8 inches in length.

Some goldfish have grown even bigger.

Imagine trying to fit an 8-10″ fish into a goldfish bowl! It just wouldn’t work. Your fish would suffer and it wouldn’t live very long at all. That’s why you need to give your goldfish a nice big tank or pond.

What size tank does a goldfish need?

Common and Comet goldfish tank size

For Common goldfish and Comet goldfish we recommend a tank measuring at least 4 feet long with a volume of at least 30 gallons. Of course, it’s a case of the bigger the better! So any more than this is great too.

If you plan to keep more than one goldfish in your tank then add an extra 12 gallons for each additional fish.

While it is certainly possible to keep Common and Comet goldfish in a tank, they can grow so large – and are so fast swimming – that they are really better suited to living in a pond.

Fancy goldfish tank size

For fancy goldfish, we recommend a tank measuring at least 3 feet long with a volume of at least 20 gallons.

If you plan to keep more than one goldfish in your tank then add an extra 10 gallons for each additional fish.

What if I have two goldfish?

Based on the rules above, we recommend:

• 42 gallons for two Common goldfish. That’s 30 gallons for the first fish and 12 additional gallons for the second fish.
• 30 gallons for two fancy goldfish. That’s 20 gallons for the first fish and 10 additional gallons for the second fish.

You might have noticed that 30 gallons is the recommended figure for a single Common goldfish or for two fancy goldfish.

If you have a 30 gallon tank and are thinking about which goldfish to buy, this might help you make your choice!

If you’re unsure of the size of your tank, you can work it out using our fish tank size calculator.

Fish-keeper’s toolkit

• Minimum 20-gallon tank for one fancy fish
• Minimum 30-gallon tank for one Common/Comet goldfish
• A filter which turns over 5 to 10 times the volume of your tank