1. What Kind of Goldfish Should You Keep in a Bowl?

Slim-bodied goldfish (like Common and Comets) are the toughest breeds.

They’re commonly sold as “feeder fish” for reptiles or given away as prizes at fairs.

goldfish eaten by snake

Provided they are properly quarantined, they are a good choice for beginners who might make some mistakes as they learn, as they are genetically tougher than the fancy breeds.

Some fancy goldfish breeds are very delicate and even slight imperfections in their environment can cause major problems for them.

So it’s not that they can’t live in bowls…

… But they are better for more advanced hobbyists who have a better handle on fancy goldfish keeping.

Fantails and Black moors are probably the two strongest fancy breeds.

Whatever fish you choose should still be small.

A full-grown adult fish (5″ or more) shouldn’t be kept in a bowl as they will need more room to move around comfortably.

All goldfish CAN get pretty big – and may outgrow a bowl – if they are given lots of fresh water.

With low hormones in the water, these fish have the possibility of continuing to grow until they can barely turn around.  This isn’t really a problem when they are little…

… But not being able to move around well once they get bigger can cause problems like muscle atrophy.

The challenge is to keep the water in good shape through filtration, plants, and careful feeding instead of lots of water changes if you want them to stay small (that’s not a bad thing).

divider3 goldfish bowl

2. How Do  You Prevent Stunting in a Bowl?

small goldfish in goldfish bowl

Image Credit: New Africa

Maybe you want your fish to get big in the long run and only want to use a bowl for a temporary home.

In that case, you will want to know how to avoid stunting your fish.

What REALLY causes stunting?


Small tanks are not the direct cause of stunting.

That’s actually a myth.

A single fish kept in a 100 gallon tank with no water changes can become stunted.

Bowls get the blame because they DO cause stunting substances to build up faster in them though, which is why this is typically more of an occurrence in them.

There are a few theories as to what really causes stunting:

1. Hormones

Goldfish produce a growth inhibiting hormone called somatostatin that suppresses the growth of other competing goldfish in its environment (source).

The theory (hotly debated among fishkeepers) goes that this hormone – if it builds up too much in the water – can cause the fish to stunt itself as it reabsorbs the hormones.

There are no tests for this hormone the average hobbyist can get.

2. Nitrates

water testing strip

Image Credit: Dmitri Ma, Shutterstock

One study found high nitrates in the water caused suppression of growth in goldfish.

There are also many anecdotal accounts of lower nitrates being linked to increased growth in fish.

The good news?

We CAN test nitrate levels.

3. Malnutrition

Feeding your fish a low-quality diet lacking in essential vitamins and minerals is more likely to result in a fish that shows poor growth.

Malnutrition can also cause a host of other health problems as well.

This should ALWAYS be avoided!

Diet can be used to control growth, but it should never be at the expense of essential nutrients or the fish risks problems.

Whether stunting is caused by hormones or nitrates (or both), there are things we can do to prevent them from building up and harming our fish – even in the confines of a bowl.

  1. Hormones can be removed by regular water changes and the use of good quality charcoal (replaced weekly) in the bowl’s filter.
  2. Nitrates can be removed by regular water changes and supplying lots of plants, as well as cultivating nitrate removing bacteria in porous substrate.
  3. Malnutrition is preventable by feeding a high quality, varied diet. Check out our article on goldfish food for more information.

Related Post: Stunted Goldfish Growth: How it Happens (and is it Harmful?)

3. How Long Can a Fish Live in a Small Bowl Before it Gets Stunted?

I’ve heard this one a lot.

That’s a difficult question to answer because not many (if any) studies have ever been done to test it.

Studies have shown it actually it isn’t the size of the tank itself that causes stunting – it’s the buildup of growth hormones from the fish in the water.


Obviously, the sooner you can upgrade, the better, if you don’t want your fish to be small.

But the good news is there are things you can do to help prevent this.

One of those is lots of large, frequent (daily is best) water changes.

Changing the water removes the growth hormone that causes stunting.

4. Are there any Big Bowls if I want a Big Fish?

goldfish in a bowl

Image credit: Unsplash


There are big bowls though that can accommodate a big fancy fish’s larger size.

If you want to keep an attractive fancy goldfish bowl with large goldfish, one that includes everything for you (filter, pump, light, substrate/filter media), you might consider the 16 gallon acrylic Biorb.  Because it’s acrylic, it’s far stronger than glass.

It’s ideal for one or two fancy goldfish.

Bigger bowls or tanks are less work than smaller ones, so the investment could be well worth it if you live a busy life.

5. Can Any Goldfish Live a Good Life in a Bowl Long-Term?

Actually, yes, they can.

Slim-bodied breeds, given the correct water parameters, can get huge.  They can grow up to 12″ long, despite how tiny they start out.

But they have the amazing ability to regulate their size in a small environment.

Now fancy goldfish don’t get so big, even under spacious circumstances.

Some breeds still grow 6-8″ on average with lots of fresh water.

But they too have the ability to regulate their growth in a smaller setup.

6. Can Goldfish Live in a Bowl Without a Filter?

Of course.

It’s been done before and will be done again.


It means more work unless you want to risk problems like oxygen deprivation and ammonia poisoning.

As in…

Daily (or even twice daily) 100% water changes.

Most of us don’t want to spend our time slaving over our fish like that, so a filter cuts down the workload to a manageable one-a-week-or-two water change.


7. How Long can Goldfish Live in a Bowl?

Usually, they don’t live more than anywhere from a few weeks to a year or two in a typical bowl setup.

But if you master water quality, they can live for 20 years or even more!

How did my Aunt’s Goldfish Live for over 10 Years in a Typical Bowl Setup?

If the fish are really hardy and the water conditions aren’t quite so extreme, sometimes they can make it for several months to a year or two (but this is nowhere near their full lifespan).

But there are some goldfish that make it longer than that, despite just about everything being wrong that can be wrong.

I get it:

Sometimes we fishkeepers scratch our head at how we can spend so much time and effort on a great setup for our fish, only to have them be outlived by someone keeping them in way more harsh environment.

But in my opinion it usually comes down to one thing…


How hardy a fish is is determined (in a large part) by it’s genetics.

Some fish – especially Commons – are just tough as boots and the hardships of improper bowl care just don’t do them in.

It’s like why some 100 year old guy can smoke cigarettes and eat bacon for breakfast everyday – and outlive someone who dies at half his age who worked out and ate healthy foods all the time.


The world’s oldest goldies tend to be slim-bodied, not fancy breeds.

So you can’t do much about your fish’s genetics, but you can try to provide them the best living conditions possible to increase their chances of living as long as they can.


Featured image credit: Unsplash