Can goldfish live in tap water? What you need to know

If you’re new to keeping goldfish, you may be wondering whether they can live in normal tap water.

Lots of beginner goldfish keepers think they can simply add water straight into their tank along with their goldfish.

However, if you want your goldfish to live a long and healthy life, this is definitely not a good idea.

Goldfish shouldn’t live in untreated tap water

Can a goldfish live in tap water?
Can a goldfish live in tap water?

Goldfish cannot live in untreated water straight from the tap. This is because tap water contains chemicals that are bad for your fish. And, even worse, can kill all of the ‘good bacteria’ in your tank.

Good bacteria develops through a process called cycling, which we talk about in more detail here.

Essentially, cycling involves cultivating bacteria that will take your goldfish’s waste (ammonia) and turn it into less harmful chemicals.

It’s vital that you maintain this delicate eco-system of good bacteria. But adding tap water can completely destroy it. The chemicals in tap water can kill some or all of the bacteria. This stops the bacteria from processing ammonia, which causes ammonia poisoning and seriously harms your fish.

What about water changes?

You might be wondering – “hold on, if I can’t add tap water, how do I do water changes?”. And of course, you do still need a regular routine of water changes.

While you shouldn’t add tap water straight into your tank, this doesn’t mean you can’t add it at all. You just need to treat the tap water first and only add small amounts at any one time.

We recommend a product called Seachem Prime for treating water. Each week, you can remove up to a third of the water from your tank and replace it with treated tap water. Just be sure to follow the instructions on the bottle.

Finally: You should never wash your filter, filter sponges, decorations or substrate (such as gravel) in tap water! These are the prime living spaces for that good bacteria we mentioned. So keep them in tank water at all times!

3 thoughts on “Can goldfish live in tap water? What you need to know”

  1. My son got goldfish for his sons. The first 2 we’re carnival fish they were dead the next morning. The next 2 came from a pet store and once again both were dead the next morning. Could it just be their tap water. My daughter in law said the chemical levels were perfect.

  2. Whenever you get new fish, if you want them to live, you have to prepare. You must “cycle” the tank first by running the filter (yes, you MUST have a filter!) for several weeks to a month before adding any fish. This is done to build up the good bacteria that eat the ammonia the fish produce. Without this bacteria fish suffocate in their own waste. This is probably the #1 cause of people’s fish dying prematurely, because beginner fishkeepers don’t know to do this.

  3. My uncle won me a goldfish at the fair in the early 80’s. Never used anything other than tap water and it was still going strong 15yrs later. Albeit he was white by then


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