Can goldfish live in tap water? What kind of water do goldfish need?

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

Lots of beginner goldfish keepers think they can simply add tap water straight into their tank along with their goldfish. But if you want your goldfish to live a long and healthy life, then letting them swim in untreated tap water is definitely not a good idea!

Tap water needs to be treated before it can be added to your tank.

Goldfish also need certain water conditions to survive and thrive.

In this article, we explain how to make your tap water safe for goldfish and what kind of water goldfish need.

Goldfish cannot live in untreated tap water

Red and white Oranda Goldfish swimming in a fish tank

Goldfish can only live in tap water when it has been properly treated to remove harmful chemicals.

Tap water contains chemicals that will 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 growing bacteria that turn your goldfish’s waste (ammonia) into less harmful chemicals.

It’s really important that your tank has this colony of good bacteria. But adding tap water can completely destroy it!

The chemicals in tap water will kill the bacteria, which stops the bacteria from processing ammonia. This causes ammonia poisoning and seriously harms your fish.

Treating Tap Water for Goldfish

You might be wondering how to add water to your tank if you can’t use tap water.

The answer is that – while you shouldn’t add tap water straight into your tank – you can add tap water once it has been properly treated.

We recommend a product called Seachem Prime for treating water.

Each week, 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.

Important: When performing water changes and cleaning your tank, 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 and tap water will kill the bacteria.

What kind of water do goldfish need?

We’ve already explained that goldfish cannot live in untreated tap water and that you need to use a product like Seachem Prime to treat your tap water before adding it to your tank. But the kind of water goldfish need goes beyond simply treating your tap water.

The water in your tank needs to have certain qualities in order to be the right kind of water for your goldfish.

There are 5 factors to get right in order to create the kind of water that goldfish need:

  1. Temperature between 20°C – 23°C (68 °F – 74°F)
  2. pH of between 7.2 and 7.6
  3. Zero ammonia
  4. Zero nitrites
  5. Nitrates as low as possible, certainly less than 40ppm

Other factors include KH and GH, but these are less critical, as goldfish. If you get all of the above water parameters right then you should have a happy goldfish!

To find out more about maintaining the right kind of water for your goldfish, check out our article on water parameters.

8 thoughts on “Can goldfish live in tap water? What kind of water do goldfish need?”

  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.

    Reply
      • Thanks for your comment Josh,

        While this may work for some people, we still always recommend treating the water with a tap safe, or running it through a carbon filter.

        Many areas have chloramine in the water, which is toxic to fish an does not evaporate.
        Dechlorinating also removes harmful heavy metals from the water.

        Reply
    • Hi Michelle,

      You need to treat the tap water with a tap safe, these are sold at nearly all pet stores, chlorine and heavy metals in the tap water kill your fish.

      The chemicals will be perfect as the fish haven’t had time to produce waste yet, since they where only in there one day.
      If they were in there any longer, you would notice that the ammonia would skyrocket.

      You need to have the tank running with the filter for at least a week before you add the fish for the tank to become safe for them to live in.

      Reply
  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.

    Reply
    • Excellent comment Miriam,

      You are 100% correct, most people visiting petstores are complete beginners, we must push better animal care education in stores and wholesales to stop people from killing so many fish and exotic animals.

      Reply
  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

    Reply
    • Hi Mike, thanks for your comment

      Everyone’s tap water is different, and while your fish may tolerate your water, someone who takes your advice that lives in a different area may end up killing their fish, as their water table contains different levels of chemicals and minerals.

      While us humans can tolerate chlorine, lead and copper because of our lined acidic stomach, fish absorb it through their skin and prolonged exposure will kill them.

      Reply

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