Can goldfish live in a bowl? Why bowls are cruel

If you’re reading this then you’re either thinking of buying a goldfish or you just got your first goldfish – perhaps it was an impulse purchase, an unexpected gift or maybe you won it at a fair. Your goldfish may be swimming around in a small goldfish bowl right now. There may even be a little bridge or a miniature diver in there too… 

But, to find out a bit more about the latest addition to your family, you’ve done some internet research. And you may already have made some startling discoveries!  

Discoveries like: 

Once you understand these facts about goldfish, it becomes obvious that goldfish bowls are not a suitable home for them.

Are goldfish bowls cruel?

Unfortunately, goldfish are often shown in bowls in the media and sold in bowls by unscrupulous or ignorant pet stores, which causes inexperienced fish keepers to think that bowls are an acceptable home for goldfish. 

They’re not.

The number one mistake made by new goldfish owners is keeping their goldfish in a bowl or small tank.

Goldfish bowls are cruel because they are far too small to provide a goldfish with the space, clean water and oxygen that they need to survive and thrive.

Here are four reasons why bowls are not suitable for goldfish:

1. Goldfish bowls are too small to filter.

Goldfish excrete copious amounts of waste because they’re large, thick-bodied fish, and they’re also always foraging for their next meal.

In order to combat the high amounts of ammonia that they put into the water through their waste and gill functions, you need a powerful filter.

2. Goldfish require a lot of oxygen.

A goldfish bowl does not have enough surface area to properly aerate the water. Surface area is key to allowing enough gas exchange to take place in order to put dissolved oxygen into water.

When goldfish don’t have enough dissolved oxygen in the water, they will start to gasp at the surface; this is not because they are actually breathing air from above the water, but because there is a higher content of dissolved oxygen towards the top of the tank.

As a side note – placing an air stone in the water does not actually release oxygen into the tank – the air bubbles serve no purpose other than aesthetic appeal. It’s the disturbance at the surface that allows the oxygen in; the bigger the disturbance over a larger surface area, the more dissolved oxygen you will be putting into the water.

3. Goldfish can grow to be huge.

Even if a bowl was a suitable home for any type of fish (which it’s not!), goldfish would be the last on the list. You should plan for fancy goldfish to grow to roughly the size of a softball at maturity, and the single tailed varieties get even larger.

Please keep in mind that you don’t want to follow the often-quoted “one inch per gallon” rule when you’re stocking a goldfish tank, or even the “two inch per gallon” rule. Both of these are very misleading because you also have to factor in how messy the fish is, how wide it gets, how tall it gets, the diet it eats, its temperament, tank mates, etc.

4. Goldfish bowls can’t handle goldfish waste.

Goldfish are super messy fish – they excrete a lot of ammonia, all the time. There is absolutely no way you will be able to properly cycle a bowl and keep the water quality pristine, even if you conduct daily water changes. There simply isn’t enough water to dilute the waste or enough room for a colony of ‘good’ bacteria to develop.

As your goldfish grows – if it even gets past the first week – the water quality will continue to deteriorate and it will lead to many completely preventable goldfish diseases.

Why you should avoid goldfish bowls

Did you know that in October 2005, the lawmakers in Rome, Italy, passed a by-law that bans keeping goldfish in goldfish bowls? Other countries, including Switzerland, have since followed suit.

But what’s so bad about the traditional goldfish bowl?

Size Matters!

There are over 200 species of goldfish, all of which are artificial, captive-bred creations that you won’t find living in the wild. These popular pet fish are directly descended from wild Prussian carp.

Like their carp cousins, some goldfish species can grow to measure up to 12 inches long or even more in some cases. Even round-bodied fancy goldfish varieties typically reach 6 to 8 inches in length.

Contrary to popular belief, goldfish don’t stop growing if kept in a small tank or bowl. The fish’s growth rate simply slows down. In some cases, the fish’s growth is stunted, leading to physical deformities and premature death.

A goldfish bowl is simply not large enough to accommodate these fish.

Poor Water Quality

Probably the biggest problem with keeping goldfish in a bowl is that the fish generate a lot of waste. That waste quickly decomposes to produce ammonia, nitrites, and nitrates, which are highly toxic to the fish.

In a 40-gallon fish tank, small amounts of nitrates probably won’t be fatal to your goldfish. However, the same nitrate levels in a tiny bowl can quickly kill your fish because there is not enough water volume to dilute the harmful chemical.

Goldfish bowls cannot easily accommodate a filter system, and without one, the water rapidly becomes polluted. Ammonia burns the fish’s gills, eventually causing suffocation and death. 

Frequent partial water changes can help, but the more the fish grows, the more waste it produces, until you find yourself changing the water in the bowl every day! Unfortunately, too many water changes deplete the colonies of denitrifying bacteria that process the fish waste, causing even more problems.

Oxygen Depletion

Goldfish need lots of dissolved oxygen in the water to thrive. Goldfish bowls have a very small surface area, making efficient gaseous exchange impossible, so the water will always be short of that crucial oxygen the fish need.

Unstable Water Parameters

Many newbies to fishkeeping assume that a goldfish bowl or small tank is easier to maintain than a large one, but that’s not the case.

Generally, it’s much harder to keep the water quality stable in a small tank. Temperature fluctuations are also far more extreme in small water volumes, as there is no buffer to modulate the changes.

Unstable water conditions are highly stressful for goldfish, compromising the fish’s immune system and leaving the creature more vulnerable to attack by parasites and diseases.

Antisocial Environment

Goldfish do best when kept in company with others of their kind, and keeping a goldfish alone in a bowl is cruel and stressful for the fish.

Pet goldfish should always be kept in groups in a garden pond or large tank where the fish can socialise.

Open-Top Dangers

Goldfish bowls don’t have cover slides or lids, leaving the top open. That presents several dangers to the fish.

  • Like their carp relatives, goldfish can jump, especially when startled. So, there’s always a danger that you’ll come home from work to find your beloved fishy friend stranded on the living room carpet because he’s leaped right out of his bowl!
  • Dust, household chemicals, and general debris can fall into a bowl without a lid, potentially poisoning your goldfish.
  • If you have a pet cat, the movement of a goldfish swimming around in a bowl can be incredibly tempting. If the bowl doesn’t have a cover, Tibbles could easily hook out your fish with her paw while you’re not around to stop her.
  • Kids are also drawn to those gorgeous, brightly colored fish in their bowls. Small children have been known to pick the fish out of its bowl and take it out into the garden in the sun. That’s not going to end well for the poor fish!

For the reasons mentioned above, a goldfish bowl is not a suitable container for a goldfish, period.

The aim of this goldfish bowl guide

If your fish is in a goldfish bowl then its life is in serious danger and you need to act now.

But don’t panic! 

In this guide, we won’t judge you, patronise you or criticise any mistakes you may have made. We will simply offer clear, straightforward advice on how to recover from a poor start to goldfish keeping and help you to look after your first goldfish properly. 

In offering this advice, we will make the following assumptions:

  • You know nothing at all about goldfish and have never kept one before
  • Your goldfish is in a bowl or a small tank
  • You didn’t “cycle” the bowl or tank before adding the fish
  • You’re willing to learn more about goldfish and you’re keen to take good care of  your fish 
  • You’re willing to make a few relatively inexpensive purchases to keep your fish alive 

We can’t promise that your goldfish will live a long life. Unfortunately, many goldfish die within weeks due to improper care at fairs, pet stores and immediately after purchase. But we do promise that your goldfish will have the best possible chance of survival if you follow this advice. 

And whether your current goldfish lives a long life or not, the knowledge you gain here could lay the foundation for many enjoyable years of goldfish keeping.

What to do if your goldfish is in a bowl 

If you have a goldfish in a bowl or small tank then you need to take the following steps as soon as possible.

Step 1: 

Stop feeding your goldfish more than once every three days. And even then, only feed a very tiny pinch of food and remove any uneaten food after one minute. 

Why? Because the more you feed, the more  polluted the water will get. But goldfish can survive on very little food for a long time.

Cut feeding to a minimum and you cut pollution to a minimum too. We 100% guarantee that your fish will not starve. Goldfish can survive for weeks without food! 

Step 2: 

Start changing 80% of the water every day.  

Why? Again, this reduces harmful pollution, as you’ll be removing polluted water and replacing it with clean water. 

Step 3: 

Before adding fresh water, ensure that its temperature matches the temperature of the water in the bowl. Also, treat the new water with a product called Seachem Prime before  adding it to the bowl.  

Why? A sudden change in temperature will  shock your fish. This shock can lower its immune system and increase the risk of illness and disease. 

Seachem Prime will remove chlorine, ammonia and other harmful chemicals from the water. Be sure to follow the instructions on the bottle. If you can’t get Seachem Prime, or a similar product, then leave the water standing in a bucket for 24 hours before each water change. This will give the chlorine time to evaporate. 

Step 4: 

Get a bigger tank as soon as possible! Ideally 20 gallons for one goldfish. If you have more than one goldfish then add 10 gallons for each additional fish. ie. 20 gallons for one goldfish, 30 gallons for two fish, 40 gallons for three fish, etc. 

Try to look for a “long” style tank. They’re a bit shallower, but they contain the same amount of water because they are longer than standard tanks. This maximises surface area and swimming space!

Why? Goldfish produce a lot of waste and can grow to be over a foot long. A big, long tank gives them room to grow, space to swim and allows a stable colony of “good bacteria” to develop. This bacteria converts harmful chemicals into less harmful chemicals (more on this later!).  

A big tank is key to goldfish health

The most important step is, of course, getting a bigger tank. A goldfish is very unlikely to survive for long in a bowl. And, even if your goldfish did somehow survive long-term in a goldfish bowl, it would almost certainly suffer significant discomfort and would not grow to its full potential.

If you’re concerned about the money needed to buy a new tank then look on eBay or Craigslist. You can pick up a second-hand tank very cheaply or possibly even free!  

If you’re worried about space then try measuring out the size of your tank in a variety of locations around your home. Most homes do have space for a 20 gallon tank some where, even if it involves moving some furniture around a bit.  

There’s no enjoyment in keeping an animal in poor conditions where it cannot grow and thrive, so get a new tank asap.

“Sorry but I’m keeping my goldfish bowl!” 

If you’re really determined not to get a bigger tank – or if it is genuinely impossible to get one for some reason – then you should look into giving your fish back to the pet store or to a friend or family member with a big tank or pond. 

If you absolutely must keep your goldfish in a bowl or small tank then you should continue to follow the steps above and add a small filter too.  

A filter will help to keep your fish alive for a while, though, unfortunately, probably not for very long.

Preparing your new tank

Once you have a nice new tank you should follow these steps to move your fish to its more spacious home: 

Step 1:  

Add a thin layer of gravel (optional), decorations (optional) and fill the tank with water (definitely not optional!). Then treat the water with Seachem Prime.  

As mentioned above, the Prime will remove dangerous chemicals such as chlorine and ammonia. 

Step 2:  

Add a filter—making sure that you choose a big enough filter for your tank! We recommend Fluval U-series filters, which come in models U1 (the smallest), U2, U3 and U4 (the  biggest). 

You should aim for a filter that turns over ten  times the volume of your tank per hour, or as close to this as possible. So, if you have a 20  gallon tank, the filter should turn over 200 gallons per hour. If in doubt, go for the bigger version! 

A filter will remove debris from the tank and will become a home for “good bacteria”. You’ll find out more about this later when we discuss “cycling”.

Step 2a (optional): 

Add an air pump and an air stone. Put the air stone into your tank and attach it to the air pump (which sits outside the tank) with some tubing. 

The bubbles from an air pump cause a disturbance on the surface of the water, which increases the amount of oxygen in the water.

Why is this step optional? The flow from the filter should cause enough surface agitation to get plenty of oxygen into your water without the need for an air pump. However, if you’re planning to keep your water at a high temperature then you should definitely get an air pump, as a higher temperature will reduce the amount of oxygen in your tank water. 

Step 2b (optional): Add a heater. 

A high temperature will encourage bacteria growth and cause your tank to cycle more quickly. 

Why is this optional? Goldfish don’t need hig  temperatures, so while a heater set to, say, 76°F or more will encourage strong growth of good bacteria and your fish, it is not strictly essential. Also, a heater will reduce the amount of oxygen available to your fish, which is why you should add an air pump if you choose to add a heater!

Step 3:  

Check that the water in the big tank is a similar temperature to the water in the bowl, then move your fish into the new tank.

You may be able to gently pour the goldfish in, rather than causing unnecessary stress to the fish through the use of a net.  

If the water temperature differs significantly between the two tanks then float the fish in a small container within the main tank for a few minutes before letting it swim freely.  

A sudden change of temperature will shock your fish. This shock will cause stress, which lowers the fish’s immune system and makes it vulnerable to illness and disease.  

Scooping the goldfish up in a jug of water (from its own bowl) and then floating that jug in the main tank for twenty minutes or so will cause the water temperature in the jug to  slowly change to that of the main tank. This  will allow the goldfish to slowly adapt to the new tank temperature and minimise stress.

What is cycling? 

So, you have a new tank all set up and you’ve moved your goldfish to its new home.  You’re doing well!

Now, as you may have heard, you need to “cycle” your tank! You may be less clear on what that actually means! Let’s take a look… 

Cycling is the process of building up a colony of “good bacteria” that will convert dangerous chemicals into less dangerous chemicals. There are three chemicals that you need to know about: 

  • Ammonia 
  • Nitrite 
  • Nitrate 

Ammonia is a very toxic chemical produced by your fish. The chemical will damage your fish’s gills and fins and eventually ammonia “burn” will cause your goldfish to struggle to breathe. Goldfish don’t survive long in bowls or tanks that contain high levels of ammonia.

Getting rid of ammonia

A goldfish will not survive long in water that is heavily polluted with ammonia, and even with frequent water changes, ammonia levels will quickly increase to dangerous levels in bowls and small tanks. 

So, we need to get rid of that ammonia. How do we do it? We convert it to nitrite. 

Nitrite is also a harmful chemical, but it’s LESS harmful than ammonia. Once some good bacteria develop in your tank, they will start to convert ammonia to nitrite.

But, as we just said, nitrite is still bad for your fish. So how do we then get rid of the nitrite? We convert it to nitrate. 

Nitrate is STILL not good for your fish. But it’s much less harmful than ammonia and nitrite.  

So, the aim of cycling is to develop a colony of bacteria that will first convert ammonia to nitrite, then convert that nitrite to nitrate. We then control the nitrate levels with regular water changes. 

Ideally, you would cycle a new tank before adding any fish. However, as we’re assuming that your fish was already in an uncycled bowl or small tank, it made sense to go ahead and add them to the larger tank and do what’s known as a “fish-in cycle” rather than a “fishless cycle”. Your tank will go through the cycling process with the fish already inside.

Cycling your tank 

So, how do we go about cycling the tank? It’s actually really easy. All you need is ammonia in the water (which your fish will naturally provide in its waste!) and the tank will naturally cycle in time. 

The difficult bit is keeping your fish alive and healthy during the cycling process! To do this, you need to regularly take water readings using a test kit (we recommend the API  Freshwater Master test kit) and change some of your fish’s water whenever ammonia or nitrite levels get too high. 

Here’s what you need to do: 

Before you start

  • Set up your tank as described earlier in this guide and add your fish
  • Buy a test kit and measure your tap water for ammonia, nitrite and nitrate – this is a base reading so that you know what you’re putting into your tank (there may be ammonia and nitrate in your tap water!) 


  • Measure a sample of tank water for ammonia and nitrite – do this before each water change. At first you will only see ammonia readings and nitrite will be zero.
  • Change at least 20% of the tank water every day. 
  • If you measure more than 0.5ppm of either ammonia or nitrite (ppm = parts per million, this is the same as Mg/l, which stands for milligrams per litre) then change 50% of the tank water until the ammonia spike is under control. 

After a few days to a week

  • You should start to see nitrite readings higher than zero. You may still get ammonia readings too. 
  • Continue to change 20% of the tank water every day. And 50%, or as much as necessary, when ammonia and nitrite spike above 0.5ppm. 

When ammonia levels fall to zero

  • Eventually you will see ammonia levels suddenly drop. At this point, start testing for nitrates.  
  • Continue testing for ammonia and nitrites too. 
  • Continue to change 20% of the tank water every day. And 50%, or as much as necessary, when ammonia and nitrite spike above 0.5ppm.  
  • Nitrate levels may be high, but don’t worry about this for now. 

When ammonia and nitrite fall to zero

  • Eventually you will see both ammonia and nitrite levels fall to zero. At this point, check your nitrate reading. It should be very high – perhaps around 100ppm.
  • Do a big water change of 75%, or however much is necessary, to get nitrate levels down to less than 40ppm. (Remember: there may be some nitrate in your tap water, which will limit how low your nitrate can go!)

Congratulations! Your tank is now cycled!  

Continue to test for ammonia and nitrites every few days, just to make sure there are no problems. Also monitor nitrates and do a big water change whenever nitrate levels  exceed 40ppm. 


You can accidentally stop the cycling process if you clean your filter incorrectly! Never clean your filter in tap water. It will kill the good bacteria living inside the filter and effectively un-cycle your tank. 

Don’t clean your filter until cycling is complete. Then, to clean your filter safely: scoop a bucket of water from the tank, unplug and disassemble your filter and gently rinse the filter sponges and the filter itself in the bucket of tank water. Then place the filter back in the main tank.

Your fish’s living situation is now much better than when it was living in a tiny bowl and your tank will be much easier to maintain from now on (no more daily water changes!).  

In the next section, we’ll talk you through the basics of a goldfish tank maintenance routine.

Your new routine 

Firstly, well done! You’ve gone from an inexperience goldfish keeper with a fish in a tiny goldfish bowl to someone who has: 

  • Kept your fish alive long enough to see its new home 
  • Set up a 20 gallon or larger fish tank 
  • Learnt about water treatments, cycling and test kits 
  • Successfully cycled your new tank! 

You should now have a much healthier and happier fish in a nice big tank.

But what do you do now? How do you look after a goldfish? 

You’ll learn more about this elsewhere on our website, but here is the basic routine you should follow: 


Add a couple of tiny pinches of food to your tank twice per day. 

After one minute of feeding, remove any excess food from the water. Don’t leave it to rot and pollute your tank! 

For a balanced diet, feed your fish a combination of flakes, pellets, bloodworms, brine shrimp and peas with the shells removed.


Test your water for ammonia, nitrite and nitrate at least once per week – ideally twice per week for the first few weeks after cycling – to make sure all your water parameters stay within acceptable limits. 

If ammonia or nitrite rise above 0.5ppm or nitrate rises about 40ppm then do a 50% water change. 

Water changes 

Change some of your fish’s water once per week, remembering to treat the new water with Seachem Prime before adding it to your tank.

That is, unless ammonia, nitrite or nitrate spike to high levels – as described above – in  which case you should change 50% of the tank water immediately. 

Filter cleaning 

You don’t need to clean your filter every time you do a water change. But giving it a quick clean once every two weeks or so is advisable. 

But remember that you should never clean your filter in tap water. It will kill the good bacteria living inside the filter and effectively un-cycle your tank!  

To clean your filter: Scoop a bucket of water from the tank, unplug and disassemble your filter and gently rinse the filter sponges and the filter itself in the bucket of tank water. Then place the filter back in the main tank. 

We can’t stress how important it is to clean your filter properly! Don’t be lazy and wash it in tap water. All you’ll do is waste all the good work you did cycling your tank.

And that’s it! Your fish escaped the dreaded goldfish bowl

Congratulations – you’ve successfully saved your fish from a goldfish bowl and started a healthy goldfish care routine! 

Of course, there’s only so much information we can fit into this guide – and goldfish keeping is a big subject! – so keep browsing the rest of The Goldfish Tank for more.

You may still have lots to learn but it will be a fun journey, and we’re here to help every step of the way.

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