Can You Put A Goldfish In Tap Water – Is Tap Water Safe?

Goldfish are native to East Asia and are a part of the carp family. A goldfish is an omnivore and can live up to ten years in an aquarium. They can be anywhere from 4.7 to 16 inches long and weigh 0.2-0.6 pounds. Goldfish are a cousin to the beautiful Koi fish, which is another type of carp. There are some very important facts that you need to know about goldfish.

You can not put a goldfish in untreated tap water! Tap water normally has a high level of chlorine and heavy metals that will poison your goldfish, ultimately killing them. As long as you neutralize your tap water to get rid of all the harmful chemicals, you can place your goldfish in tap water.

Today, we will cover a few things that you need to know about the goldfish. We will tell you exactly how to ensure that your tap water is safe, what foods to feed your goldfish, along other useful information about goldfish. First, I am going to give you a little bit more detail on the goldfish.

Basic Goldfish Information

The BBC believed, in 2008, that the biggest goldfish was 19 inches long and lived in the Netherlands. Goldfish can get up to approximately 14 inches long if you keep them in an outdoor pond. If you have one or two in a 10-gallon tank, they will get no bigger than two or three inches in length.

With many different species of goldfish, you get a variety of shapes, colors and fin configurations. Some versions of goldfish solely live in aquariums. Currently, there are over 300 breeds of goldfish, which originated in China.

  • Common goldfish
  • Black telescope (popeye)
  • Bubble eye
  • Comet
  • Fantail

That is just a very small handful of different goldfish. My personal favorite is the Black Telescope. They have unique protruding eyes, and I just love the way they look versus the common goldfish.

Goldfish are classified as coldwater fish. For just one goldfish, it is recommended that you have them in a 10-gallon tank. If it is a smaller species, you are safe to have two in a 10-gallon tank. The temperature in your tank has a large range. This will depend on a few factors, which we will cover shortly.

Tap Water & Your Goldfish

Even if your tap water is considered ‘safe to drink’, you can not just take a goldfish home and put him in a tank full of tap water. Out in the wild, a goldfish will be found in murky water. This sounds strange, that they can not go into tap water but they live in murky water in the wild.

The murky water doesn’t have the chemicals that tap water has, that harm goldfish. The harmful components in tap water, that you cannot see; lead, zinc, chlorine, and chloramine as long as a few other heavy metals. These will actually poison your goldfish, which will ultimately end up in your goldfish passing away. Let’s take a look at why.

ChlorineUsed to disinfect public water systems and eliminate E-Coli. It is safe for humans, but toxic to goldfish. Some places will use chloramine vs chlorine, which is even more dangerous. Since goldfish use their gills to breathe, you MUST dechlorinate your tap water. Chlorine causes a terrible burning feeling and makes breathing especially difficult for your goldfish.
Heavy MetalsIn some areas, tap water contains copper, lead, mercury, zinc, and cadmium. All of these heavy metals have an adverse effect on humans as well as fish. The effects on fish are worse because of their much smaller size.
High concentrations of these heavy metals will create pathological changes as well as weaken the immune system of the goldfish. Heavy metals cause immense stress in your goldfish which affects their well-being.

How To Treat Tap Water On Fish Tank

Goldfish are messy fish and sometimes need frequent water changes, even with a good filtration system. You will need to do a 15-20% water change, every week.

There are two ways that you can make sure that your tap water is safe for your goldfish. They are both very easy to do, and they will ensure that your goldfish stays happy and healthy. 

  1. Use a good water conditioner! Pet stores carry a variety of different water conditioners, by many manufacturers. Make sure to ask the pet store associate which one is their best seller. You want to make sure you are purchasing one that is going to get rid of all of the harmful chemicals in your tap water. If it is feasible, you may want to have your water tested beforehand. This will tell you exactly what components are in your tap water. Then you can get the most specific product for your situation. 
  1. Use pre-treated or filtered water! This is also available at pet stores. This type of water is completely free of any chemicals and can be put straight into the tank when you arrive home. Pre-conditioned or filtered water can be expensive in the long run, because you are going to need quite a bit to perform your water changes. 

Extra Aquarium Water Tips

Good bacteria live in many areas of your aquarium; filter sponges (other filter parts) and decorations. NEVER was any of your filter parts in tap water when you do your water changes. Again, tap water will kill all of the good bacteria which will affect the cleanliness of your aquarium. 

You want to replace at least ⅓ of the water in your tank during water changes. Make sure you treat the new tap water before you put it in the aquarium. Use a gravel vacuum to remove first, leftover food, and other debris. 

Clean aquarium decorations, walls, filter parts, and gravel in filtered water. You also need to make sure that your water temperature of the new water is relatively close to what is in the tank. You do not want to shock your goldfish or cause them any other undue stress.

How To Care For A Goldfish

Here, we are going to cover a few other important things to boost your knowledge of the goldfish. You also want to do extensive research, on your own, on the goldfish. This gives you a lot of insight on how goldfish are going to behave, what foods to give and not to give, and you can easily recognize symptoms of illness and injury. Knowledge is power and can sometimes save you a lot of money and heartache in the long run. 

Goldfish Food: Goldfish are omnivores. They will readily eat goldfish flakes, floating pellets, and live plants. You can also feed them fresh, frozen, or dried eggs, insects, and larvae. Feed them two to three times a day according to the packaging directions. 

Temperament: Goldfish, for the most part, are peaceful fish. They prefer to be kept in a tank in pairs of two, minimum. They can get a little snippy with fish that are bigger, smaller, or slower than they are. They prefer a large open area to swim. So a few decorations are okay, but definitely do not overdo it. 

Tank Size: It is recommended to have a 10-20 gallon tank for 1 adult goldfish (30-40) for the bigger goldfish species. Add ten to twenty gallons per fish, after everyone that you have in the aquarium. A 40-gallon tank is perfect for 2 adult goldfish. Their temperature range is 60-80 degrees.

Since they are cold-water fish, most people will keep their aquariums around 70 degrees. Not too hot, but not too cold either. You also do not want to put them in planted tanks, as goldfish love to uproot and eat plants. Your pH needs to be between 6.0 & 8.0. Goldfish like heavy filtered, low-flow water with a minimum current.


NO, you can not put your goldfish in tap water, unless you treat it and neutralize the harsh chemicals that are found in tap water. Check your pet store or online for the most popular water conditioner for a goldfish tank. Their tank needs to be free of anything harmful such as; chlorine, chloramine, zine, mercury, and more.

If you take good care of your goldfish and do not have any of these nasty chemicals in the water, then plan for your goldfish to live at least 10 years, inside an aquarium. Remember that the temperature range is 20 degrees (60-80) degrees is the perfect temperature.

This means you may or may not need an air conditioner or a heavy comforter on your bed. If you can keep your house (in particular, the room) where your goldfish is, up to temperature, then you will not need to buy a heater. Just a good filtration system and water conditioner.

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I'm passionate about fish pets and love sharing everything I learn about them.

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