Tank Size Explained

Today I’m going to shock you with a statement you would expect to hear from an uninformed pet store employee:

Goldfish don’t NEED a big tank.


“You’re joking, right?”

No, I really mean it.

After nearly 20 years of goldfish keeping, I’ve come to realize that all the hype about making sure your goldfish has to have an ocean to swim in is just that…


And this is why:

How Many Goldfish Can You Put in Your Tank?

That, my friend, is the $64 million dollar question.

I’ve seen countless unsuspecting fishkeepers – new and experienced – get totally ripped to shreds (verbally) for posting a photo of their goldfish in “too small” of a tank (or even more horrifying, a bowl) online.

It’s like they might as well have posted:

“I’m an animal abuser who loves torturing goldfish.”

Why all the hate?

Because they’ve broken the unstated “RULES.”

The question is… exactly what rules?

You’ve probably heard any of the following stocking ratios for goldfish:

  • 1 inch of fish per gallon

  • 1 inch of fish per square foot of surface area

  • 10 gallons per fancy fish

  • 20 gallons per fancy fish

  • 20 gallons for the first fancy fish plus 10 gallons for each additional fancy fish

  • 30 gallons per fancy fish

  • 30 gallons per slim-bodied fish

  • 40 gallons per slim-bodied fish

  • 50 gallons per slim-bodied fish

  • 55 gallons per slim-bodied fish

  • Slim-bodies should only be kept in a pond

And these aren’t all.

So you can see that there’s all kinds of ideas floating around out there on exactly how many gallons of water a fancy or a slim-bodied fish needs…

… And precious little evidence to show why one is superior to the others.

No wonder people are confused about goldfish tank size!


When it comes down to it… those “rules” (none of which are in agreement) are just different guidelines people have made up over time, usually based around doing a 25% water change once every week or two and having a typical filter.

The problem?

None of them take into account that you might be able to have lots of plants, more water changes, carefully regulated feeding or greater filtration capacities – things which can really offset having a smaller water volume.

Every situation can vary drastically.

So what it all boils down to is there are no set “rules” about tank size – there are too many other factors at play from fishkeeper to fishkeeper.


Listen carefully now:

Because water volume does NOT have a direct influence on the health of your goldfish (provided the fish can swim around enough to prevent muscle atrophy).

Water quality does.

Tank size can only play a direct role in the following:

  1. How frequently you have to go between water changes
  2. How big of a goldfish you can house (i.e. swimming room)
  3. And (potentially) aggression between more concentrated tank mates.

If you’re a beginner wanting a good starting point – a general suggestion – and you have the space and money, feel free to start out stocking your fancy goldfish tank at 10-20 gallons per fish.

Or 20 gallons, or 30, whatever you like.

A bigger tank means less work for you because the greater water volume dilutes toxins between water changes.

It also means your fish can get bigger comfortably.

This is more desirable if you are wanting your fish to get large.

As the hobbyist, you choose your goals.

If you want to keep a chunky 6-8″ fancy goldfish or even a 12″ slim-bodied fish, there’s no question that you’ll need more space for them (yes, many of them can get that big with the right conditions).

Some find their foot-long single-tailed fish appreciate having as much as 55 or 80 gallons to itself, others feel 30 or 40 gallons is enough.

If you’re looking in your tank and really feel like your fish needs more swimming space, by all means go for it – pets are not fun to keep if you feel like yours is not happy.

As the owner, you know your fish best.

So more power to you 🙂


Some fish don’t seem to appreciate lots of space, others do, sometimes it just depends on the fish.

But maybe you’re just starting out with a little 2″ Comet you brought home from Walmart or a funfair.

Maybe you’re on a tight budget.

And maybe you don’t have a lot of room for a big tank.

Some people will go ballistic and tell you, “That fish is gonna get huge! Don’t you know it can’t live in such a small space?! You need to give your fish away, take it back to the store,” etc.

Not me.

And here’s why:

Goldfish CAN Grow to the Size of Their Tank

Yes, you’ve heard it right:

Goldfish produce a growth inhibiting hormone (GIH) that builds up in the water.

When that water is changed all the time, the hormone is removed and the fish continues to grow.

A bigger tank helps to dilute this hormone, which is why goldfish tend to get really big in a big tank.


In a bowl or small tank, that hormone is very concentrated (unless lots of water changes are done all the time).

So it limits the fish’s growth.

And this is not the bad thing a lot of people think it is.

Many of the oldest goldfish in the world – the ones that have made it into their 30’s and 40’s, at the highest end of a goldfish’s lifespan – are what people would call quite undersized.

Really, they’re just environmentally stunted.

But their unusually long lives prove that they are healthy (an unhealthy, weak goldfish can’t live that long).

(Read more about why stunting isn’t a bad thing here).

Obviously, if your goldfish has already grown big, it’s too late for stunting to happen and it will need a bigger tank in order to have sufficient swimming space.

So only young fish that haven’t grown much should be kept in a smaller space to avoid muscle atrophy problems.

That said:

Even some full-grown adult goldfish will never get to be monsters with tons of space, clean water, nutrition and time.

These can be genetically stunted and can also do quite well in a smaller space.

More Important than Goldfish Tank Size: Water Quality

Instead of getting obsessed about the tank size itself…

It’s far, FAR more important for a goldfish to be provided with clean water (in my opinion).

The way I see it:

A small, healthy fish is just as legitimate as a big healthy one.

As long as your fish is well-cared for and its needs are met, it’s a matter of preference – what works for your lifestyle and your objectives as a hobbyist.

I’m not going to say you’re wrong! 🙂

But Aren’t Small Tanks Too Dirty or Toxic to be Safe Fish Homes?


There’s this idea that smaller tanks = bad water quality.

Obviously if that was the case I wouldn’t advocate them, because bad water quality is not to be tolerated – clean water is a basic need of goldfish.

Well, from what I’ve observed over the years, goldfish tank size is not to blame for that.

I’ve seen countless people who have a massive, lightly stocked tanks and several filters – with SICK FISH because their water quality is totally out of control.


When a fish is sick in a smaller tank, the issue isn’t the size of the container (like so many immediately assume) – it’s very likely the water itself.


It might take more diligence to balance the water chemistry of a smaller tank…

… But it’s not impossible.  Not by any means.

It’s been done many times.

Focus on having a strong colony of good bacteria, feeding lightly, testing the water and performing water changes when needed and you’re on your way to a healthy environment for your fish.

That said:

I still recommend using an ammonia alert card you can check on daily, especially when you are first starting out with a bowl or a small tank – just to be on the safe side.

It will help give you peace of mind. 🙂

Balancing Matters

Now, if you put 8 goldfish in a 10 gallon tank, it’s going to take a lot effort to keep the water quality under control.

You’ll also have less room for error, and there’s a chance they might pick on each other more.

A word on aggression…

Some people find that they have more problems with aggression when there are more goldfish in a smaller space.

Others don’t have a problem with this.

(And then there’s me, who has one fish in a 30 gallon tank all by herself who won’t tolerate anyone else, so go figure. 😛 )

It can depend on the fish’s individual personality.

My theory is there is less chance of trouble if all the fish are young – and introduced to the tank at the same time rather than one by one.

Sometimes aggression settles down once a “pecking order” is established.


If your tank is totally packed with fish, it’s going to require a LOT of work to keep it safe for your fish.

So if you don’t want to spend your life slaving over them, a big tank can help free up your time.

In a more heavily stocked tank, overfeeding one of the biggest mistakes, followed by inadequate filtration and maintenance.


Clean water isn’t all there is to keeping your goldfish healthy.

Other aspects of their care are just as critical, such as proper nutrition and quarantine protocols.

Wrapping it all Up

I’m sure not everyone is going to agree with me on this.

I also find that most people who criticize those who keep their fish in a small tank or bowl have ironically never owned a goldfish that made it past 10 years old, let alone 40.

But if you have any additional science-backed evidence that proves smaller tanks or stunting is harmful, I’d love to hear it in the comments below.

Have you learned something new?

Drop me a line!

4.5 90% from 42 ratings
Rating 4.5 90%


  1. Neelam February 2, 2019 at 5:05 pm - Reply

    Very nicely explained. I love to follow pure goldfish as I am a beginner and it really has helped me a lot so far with 3 tiny baby goldies ?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 4, 2019 at 6:58 pm - Reply

      Glad you liked it, Neelam!

  2. Louis van de Kant February 5, 2019 at 7:17 pm - Reply

    I love the info, and I will use it for my goldies, the only question I have (for schoolpurposes) is: are there any sources you used? Or is this all from experience?

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish February 5, 2019 at 7:43 pm - Reply

      It’s a scientific fact that goldfish produce growth inhibiting hormone somatostatin. It’s also a scientific fact that poor water quality, such as high ammonia levels, directly influence the health of goldfish. Other than that there is not much scientific evidence out there on the topic of tank size, it really does come down to my own experiences fishkeeping and that of other fishkeepers. Hope that helps 🙂

  3. SomeDude February 7, 2019 at 1:20 am - Reply

    Finally someone who makes sense.. fish enthusiasts can be a little…..over the top

    Rating: 5
  4. Melicia February 12, 2019 at 12:28 am - Reply

    I agree with everything you have written! I have several different tubs and tanks with different amounts of fish. 2 100 gallon stock tanks each with 10 5-6 inch pond golds. 1 10 foot long 300 gallon trough with 20 4-7 inch pond golds and 1 45 gallon tub with 4 5 inch pond golds. I have had all my fish more than 3 years and they were all tiny (half inch ) feeders from the pet store when I first got them. they are all very healthy and I assume happy. I think it is because I have made homemade 5 gallon bucket bio filters for each container. also I use plant filtration/aquaponics. some are house plants some are veggies, and even 1 4 foot tall dwarf clementine fruit tree. I need to mention however I never do water changes. I only top off tanks when needed. and clean out filters once a month by way of a quick flush with a hose. I will say it is the plants that keep the water clean! also all my fish are indoors next to windows for sun. I loved reading your article thanks so much!

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 12, 2019 at 12:38 am - Reply

      Thanks for sharing, Melicia! Aquaponics are an awesome way to manage water quality. Personally I hate doing water changes so the less work the better! Would love to see pics of your setups. 🙂

  5. Ross February 14, 2019 at 9:28 am - Reply

    I found this via google, very helpful, i just wish I had seen it before my wife decided to purchase 2 fancy goldfish in a 6 gallon tank. The water changes are insane and I feel awful for the fish, it’s not even nice to have to look after them in this way. I’m looking to buy a 23 gallon tank and I hope it makes the water changes more acceptable for the fish. Would you think it might be ok? There is so much information out there and different recommendations!

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish February 15, 2019 at 9:39 pm - Reply

      More water is helpful for sure, but your filtration may not be effective enough. If that’s the case even a large tank will be problematic.

  6. Sabrina February 16, 2019 at 8:12 pm - Reply

    Personally I think there is middle way.
    I mean mine is 8 gallons for two fish!
    Obviously not eight fishes but two is good and if they grew is better change it!
    Also largest is worst is, like dogs they feel scarry of wide spaces!
    Obviously I don’t put something inside, maybe the ‘tank’ of 0.26 gallons inside for when I put them inside.
    But isn’t good idea put two fish in large space.

    Personally I for the middle way.
    5 gallons don’t create problems for change water and other(is easier control the water) things.
    Obviously, I think 2 gallons per fish.

    Ps: sorry I’m European so all thes things confuse me. I don’t know how gallons work.

    Rating: 4
    • Pure Goldfish
      Pure Goldfish February 18, 2019 at 5:41 pm - Reply

      Thanks for sharing your input, Sabrina!

  7. Laura Sell February 17, 2019 at 9:58 am - Reply

    I keep tropical fish, but this week have been in the lucky position to rescue 3 small goldfish that were going to be flushed down the toilet!!! I have put them in a spare 11 gallon tank with sponge filter as that’s all I had. It is not ideal, but I believe it better than the fate they were destined for! (even if that means daily water changes) Your site has been most helpful, and I do plan on upgrading the fish to a much larger tank when they grow a little. Thank you for the advice and non judgemental attitude.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 18, 2019 at 5:41 pm - Reply

      Good job saving them from that fate, Laura! Thank you for your kind words.

  8. Sadie Gold February 20, 2019 at 1:34 am - Reply

    I am SO relieved to read this! I currently have 3 goldies and I love them all dearly. One is a sarasa comet (got her for Christmas, presumably from a petco/petsmart), one is a common (rescued him from a fair because I felt bad), and I have a little fantail (he’s from a family owned specialty fish store). They get along famously, and don’t worry, the fantail eats enough! He is faster than my single tails to the food because they are so lazy! They are in a 55 gallon and everything I was reading online made me feel as though I would have to replace my new tank that I just got used a month ago eventually. It was all I could afford and I felt that it would suffice for my precious little ones! But then I was reading so much conflicting information and I got so confused! I believe my single tails are slightly stunted due to their past, but they are both still healthy and very active. I can not bear the thought of giving them away unless they truly seem to show signs of suffering, which they don’t. All three choose to be near each other for a majority of the day, and they all dart around the tank with healthy, unclamped fins. There are no signs of parasites/diseases, and no nipped or deteriorating fins. So… I gather that I will be able to keep them for the rest of their lives in a 55 with 50 percent water changes every week- two weeks, a diet of sinking flakes and mushy veggies/fruits, and a strong filtration system?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 20, 2019 at 4:58 pm - Reply

      Most of the world’s oldest goldfish are/were stunted. Healthy, with good water quality, even if the fish stays on the smaller size, means you are taking good care of them 🙂

  9. Hadzirah February 22, 2019 at 3:52 am - Reply

    Thank you so much for this information. I have 2 Shubunkins, 1.5″ and 2″ and 4 little guppies in a 5 gallon tank. I do 80% WC almost every single day if I see any abnormalities in the tank like cloudy water, weird behaviour, weird swimming, being all passive or even if their coloration looks weird. I use Nutrafin Aqua plus too. Used API test kit and so far Nitrite and Nitrate are 0. But so far the only abnormalities I came across are my 1.5″ Shubunkin likes to poop more than the other one. The water in the tank isn’t cloudy but just lots of tiny debris keep floating around since I use air stone. The fish loves to play around the tank like they have no problem at all. I think they are happy in there. One of my guppies love to tease the Shubunkins by pecking on them but the Shubunkins don’t seem to mind… they’ll just swim away if they don’t like it and that’s all. I was worried if they feel stress and all but I don’t see any stressed sign… I do wanna buy a 10 gallon tank for them in another 2 weeks or so. I don’t plan on adding more goldies and I will only focus to take care of just these kids.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 22, 2019 at 6:59 pm - Reply

      Glad you liked the post, Hadzirah! Sounds like you are trying to take good care of your pets!

  10. C Funke February 25, 2019 at 6:40 am - Reply

    Great stuff. Glad I stumbled here! Just moved house. Had the old boys (3) in 50 gallons and then 3 weeks or so in 10 before getting the old tank up and running. Got filters and plants in today. Everyone is healthy but could really use a bit of extra time between changes. Please talk more about aquaponics!

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 25, 2019 at 10:00 pm - Reply

      I plan on writing a complete aquaponics tutorial soon, so check back. 🙂

  11. Matt February 27, 2019 at 11:07 pm - Reply

    Music to my ears, hosestly the things you read online about goldfish is rediculous, you are exactly right the the above, I have had a goldfish won at the fair, it’s first three years we lived in a small tank (bought at the fair) it was happy all the time in this around 6 litres……… now I decided to buy it a anniversary present for doing so well in life, now it’s in a 60l tank and dominates against and 2 rosy barb, another cross breed goldfish, and colony of cherry shrimp….. this goldfish is hardy as they get… goldfish for KING

    Rating: 5
    • Pure Goldfish
      Pure Goldfish February 28, 2019 at 9:38 pm - Reply

      Happy you liked the post, thanks for sharing your story!

  12. Jenn March 5, 2019 at 7:37 pm - Reply

    So it would be okay to keep one goldfish in, say, a five gallon tank? Would keeping it in that size of a tank keep it small? There was a stunning multi-colored goldfish I saw at a Petco feeder tank, but I’d only want one.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 6, 2019 at 12:25 am - Reply

      The size of the fish is more dependent on water than tank size. Just because it is in a small tank does not mean it will not keep growing if it is given access to lots of fresh water. Hope that helps 🙂

  13. Daniel Hoyle March 5, 2019 at 10:48 pm - Reply

    Hi there, interesting read, thanks for the info, out of interest i recently aqquired a slim bodied goldfish whos around 5 years old, he was being incorrectly cared for so i thought i would try give him a fresh lease of life, hes currently in a 57 litre tank and seems fine (doing regular water changes and checks etc) however i recently decided to add another small shubunkin for his company, hes only a baby in comparison, and since doing so the original fish just chases him around nipping at him, now the baby has hidden behind a rock feature where the bigger one cant get to him and has been there hours and wont come out. Any ideas i feel terrible for the little baby fish he must be petrified.

    Rating: 4.5
  14. Ari Snyder March 17, 2019 at 11:53 pm - Reply

    Hi I have 2 small goldfish like 2.5”, they live in a VERY SMALL tank and I clean it COMPLETELY every 2 weeks. Both display normal behavior but one is turning white and isn’t growing scales yet the other one has his normal color ( reddish orange) since day 1. And I prefer your opinion after all the mean comments in Facebook… what can I do about this?

    Rating: 3
    • Pure Goldfish
      Pure Goldfish March 18, 2019 at 6:24 pm - Reply

      I would look into testing your ammonia levels. Those are the biggest problem with smaller water volume. Missing scales could mean flashing from irritants in the water, with smaller spaces more frequent cleaning is often required.

  15. Morgan March 18, 2019 at 5:56 am - Reply

    Hi! I really enjoyed reading this because I’m looking into a fantail goldfish, and I really want my fish to be happy and live a long time!! I need opinions. I planned on buying (even rescuing, if you ask me.) a fan tail from my local Walmart. I don’t have much room, but would a 5 gallon tank suffice? I’m not planning on buying another fish, just want one. I’ve searched low and high, I just want my little guy to be happy & healthy.

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish March 19, 2019 at 5:01 pm - Reply

      If you do lots of water changes you might find the fish outgrows the tank, so it really depends on your husbandry. Relying on filtration and plants more can help avoid so many water changes.

  16. RhiLady March 19, 2019 at 2:20 am - Reply

    This is SUPER helpful, and makes me feel so much better about having my three smol feesh in a ten gallon tank. They were NOT happy in the 3gal I had originally had them in for all of a day or two, which-no wonder! They’re fine in the 10gal, however. I’m just waiting on the supplies to balance the water quality, as well as pellets so that I can stop feeding them fish donuts (aka flakes), because WOW did I not get told that pellets were better for them at the store. As soon as I get those in two days, it should be great. I’ll be doing a 90% change tomorrow, so hopefully they’ll be okay while we wait for the rest of their stuff.

    SO glad I found this site!

    Rating: 5
  17. RhiLady March 19, 2019 at 2:22 am - Reply

    That being said, can’t wait for the bacteria to arrive, because I made the huge mistake of not cycling my tank first, because I was an idiot and didn’t do my research well enough. >_> Oops.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 19, 2019 at 4:57 pm - Reply

      Thank you for your kind words! We all make mistakes, goldfish keeping is a learning process 🙂

  18. K March 20, 2019 at 10:35 pm - Reply

    So… A goldfish will produce a growth inhibiting hormone and therefore can be kept in small tanks, even bowls.

    Sounds logical enough.

    It’s imparative to provide the fish with fresh water. Doing so removes the growth inhibiting hormone. Removing the growth inhibiting hormone means the fish will continue to grow. So the fish will eventually grow to it’s full adult size regardless of the size of the tank.

    Do you see the cognitive dissonance here?

    Rating: 1
    • Pure Goldfish
      Pure Goldfish March 21, 2019 at 4:36 pm - Reply

      That’s why I say that fresh water is not imperative. Clean water is.

  19. ACM March 21, 2019 at 4:16 am - Reply

    Hi I just came across this page, my roommate’s boyfriend just bought two small goldfish (like carnival sized) and right now they’re keeping them in one of that temporary 2-gallon ones, I’m going to try and convince them to get a 10 gallon one (as that’s the max size we’re allowed to have) but none of us are fish people like at all so I was wondering if anyone has any advice on how to care for them. Right now they’re just sitting at the bottom of the tank and they haven’t eaten I’m not sure if they’re just stressed from the new environment and that’s why? My main concern is the cleaning how exactly do you partially change the water?

    Rating: 5
  20. Henriette Andersen March 24, 2019 at 2:43 am - Reply

    Thank you for this! I’ve been feeling a bit insecure about this “too little tank”-stuff from what I read online, even with my 30 gallon tank. I have one fancy goldfish who is around 3.5 years. I had two before, but one died after a period of over feeding from an automated feeder when I went for a holiday. I have not introduced more fish, and frankly he seems to have a good time in his 30 gallon tank at the moment. Ever since the incident I have been careful to never feed too much, and change water regularly. Since the tap water here in Norway is without any salts, magnesium or calcium, I add some salt and alabaster gypsum (carefully measured to get right GH) after each water change, and it has worked well for the last years. We often walk near the tank because the flat is soo small, and he likes to swim to the glass and see what’s happening (mostly because he hope it’s food), or he just swims along nibbling at plants or searching in the gravel.
    I have been considering upgrading the tank and introduce more fish, but at the same time I’m a student who don’t have that big a budget, don’t have too much space, like to have only one fish to monitor, and he seems to be healthy.
    I believe that him being healthy and active is the most important thing. And I agree that the water quality is the most important thing, not necessarily the space. I’ve seen the same fish being both sick and healthy in that same aquarium, and that is only about water quality. Maybe it would be easier with more water, but after I got a hang of it and got my routines, I think I will still manage with less than the biggest tank in the world. My plan is to keep this guy happy for a long time. 🙂

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 25, 2019 at 3:30 pm - Reply

      Definitely no need to feel insecure 🙂 Thanks for sharing!

  21. Charlotte March 25, 2019 at 2:15 am - Reply

    Hey there! This is so helpful. I have a beautiful 5ish gallon biOrb tank with a filter and have been doing my research, but really want to get a single goldfish to put in there. How frequently would you recommend doing partial or full water changes if I were to go this route? I would consider upgrading to a bigger tank down the road if the fish grows enough. Thanks!

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 25, 2019 at 3:34 pm - Reply

      Water changes really depend on your water test results. If you have good filtration less is required. Ammonia and nitrite must always remain 0, nitrate never above 30ppm.

  22. E March 25, 2019 at 11:01 pm - Reply

    I love the post! One question though for getting beginner tanks. We recently got two 1 gallon tanks and were debating how many small goldfish could live in there. Would two baby goldfish be enough for each tank?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 26, 2019 at 7:47 pm - Reply

      You might want to take a look at this article on bowls. Hope it helps 🙂

  23. SM March 26, 2019 at 2:18 am - Reply

    I am thinking about getting 2 goldfish. What would be the best tank setup for the smallest tank with the least time cleaning (tank size, filter type/size, % water change frequency, food type, etc.)? Also, how much time would need to be spent cleaning/changing water with this setup? Thank you!

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 26, 2019 at 10:40 pm - Reply

      Too many unknowns for me to give an accurate answer to this, there are at least a dozen variables. Some people have 2 goldies in a 10 gallon and only need water changes every other week. Others have 1 in a 30 gallon and need bi-weekly water changes. Filtration plays a factor for sure but food amount, plants, substrate, fish size/waste output, cleaning methods and more make this too difficult to say for sure. It basically comes down to trying things and seeing what works best for you 🙂

  24. Dave March 26, 2019 at 6:24 am - Reply

    I agree,I have 2- 5″ Goldfish ,one with a large tail and one common Goldie, I bought them as tiny feeder fish and they have been Happy and Healthy in a 5 gal Fishtank ,it sounds small but they have swimming room,Ive had them for bout 2 years now. Once before I had three Goldfish in a 10 gal tank and they got so big there tails came outa the water when they pecked at the bottom,I had to relocate them.Anyway nice to here what was said here,and good clean water is the trick,and if they get so big there comin outa the water then they need a new home,and watch them if they look happy and healthy they probably are.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish March 26, 2019 at 10:41 pm - Reply

      Good points Dave, thanks for sharing!

  25. Jessie April 1, 2019 at 4:53 am - Reply

    I might have misread, but it seems to me like this is saying that goldfish will be stunted in smaller tanks because this hormone builds up in the smaller amount of water more in between water changes. Didn’t this also say that you need to do more frequent water changes in a small tank, though? Basically, if we’re doing water changes often enough to keep things like ammonia from building up and keeping the water fresh (as instructed here), how is the hormone going to have any effect?

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish April 1, 2019 at 4:13 pm - Reply

      Water changes are not the only way to control water quality. Filtration, plants, careful feeding and a strong bacteria colony is the focus for keeping a smaller healthy fish. With the right setup and routine you shouldn’t have to do water changes to control ammonia and nitrite, only nitrates. Smaller tanks that have ammonia problems are out of balance on some or all of the points above. Hope that makes sense 🙂

  26. Victoria April 2, 2019 at 1:35 am - Reply

    Yesterday I bought two small Fancy Goldfish, each one about 2-2.5 inches in length. Today I put them in their new 2.5 gallon tank. I was going to get a larger tank, but didn\’t exactly notice how small the space really seemed until I put them inside. They each have enough room to swim around (They don\’t have to stay in one spot due to lack of space or anything) but their space does seem pretty limited, and I just felt like they might get bored or depressed with such limited space. A bigger tank would be expensive, (I\’m just 16, working a part time job, I had spent a little over $70 in total yesterday on everything needed for these fish) But of course if their sittuation truly sounds unacceptable, or could possibly keep them miserable, I\’ll pick up a larger tank asap to keep happy fish. If I could get a more experienced opinion that would help me a lot please, thanks.

    • Pure Goldfish
      Pure Goldfish April 2, 2019 at 3:55 pm - Reply

      If you feel like your fish aren’t happy, I would by all means upgrade. And personally I wouldn’t do 2 goldies in that size of a tank. 🙂

      • Victoria April 3, 2019 at 12:04 am - Reply

        I thought so 😊 I’m looking for a ten gal I can keep them in as their more permanent home in the near future, thanks!

        Rating: 5
  27. Gagan April 2, 2019 at 5:06 am - Reply

    So…. Is it okay to have 9 goldfish in 60 gallon tank?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 2, 2019 at 3:56 pm - Reply

      Provided you keep the water clean. You might need heavier filtration when you stock more heavily.

  28. Michelle April 2, 2019 at 9:21 pm - Reply

    I’m about to take my daughter’s three goldfish that I bought two days ago back to Petsmart – I only got a 2.5 gallon tank for it, and one of them jumped out of the tank (I must’ve walked in the room right after it happened cuz he survived after I put him back in the water). I called petsmart and asked if they had any lids for that size tank there (they don’t), and then the lady was telling me I’d need a filter for my tank and that I’d eventually have to upgrade to a bigger tank because they won’t be able to grow and it can be very painful for them. I don’t want that, which is why I am about to return them. I didn’t realize goldfish were higher maintenance – I honestly just wanted something low maintenance for my daughter. She recommended a beta fish. Thoughts??

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish April 3, 2019 at 3:36 pm - Reply

      I have yet to find any evidence that it is painful for them not to grow huge. But a betta probably would be a better fit for that tank than 2 goldies.

  29. Tijuana April 4, 2019 at 1:46 am - Reply

    Hi, I have 4 fantails in a 55 gal. I have had them for a year now. They are pretty boring and I wanted to add a few smaller fish with them. Other than the petshop telling me no, because my tank is too small they said no other type of fish can go with them because they give off too much ammonia and waste. Not even a bottom feeder or snail. Is that correct?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 4, 2019 at 5:11 pm - Reply

      If your filter can handle the ammonia and waste, no reason not to. Snails help the cycle because they break down the waste.

  30. Mélodie April 7, 2019 at 8:09 pm - Reply

    Yes, you can \”trick\” a small system with a right schedule of water change, good filtration, etc. I have a 125 gallons with 7 goldfish and I think I\’m in the edge of stockage limit! I can\’t add anymore. The adult fish are huge. I had one who has 12 inch long and unfortunately, he passed away because of an accident. The other big have 9 inch (maybe one of them will grow a little more this year) and the little one continue to grow… I\’m agree that each fish have a potential size determined by their genetic. Some goldfish can be really big and some can be a little less big. The think I\’m not agree about that article it\’s that some people will be proud to have a five years old goldfish with a 2 inch of size. For me, you just washed the real potential of your fish. A goldfish is a BIG FISH. Not small. Why do you show proud to have a St-Bernard with the size of a chihuahua?

  31. Savahana April 8, 2019 at 3:46 pm - Reply

    I wish I would have known all of this stuff before getting a goldfish, it died not too long ago and it was in a 5gallon. I finally feel confident to buy another fish and be in the hobby as a beginner.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 8, 2019 at 11:40 pm - Reply

      Glad you liked the post, Savahana!

  32. Megan April 8, 2019 at 4:45 pm - Reply

    I just bought a 54 litre tank and I’ve read so many things saying that it’s not even big enough for one goldfish and I was hoping to get 2, would 2 goldfish be ok in a 54 litre tank?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 8, 2019 at 11:41 pm - Reply

      I think you’d be just fine.

  33. nicole April 8, 2019 at 8:34 pm - Reply

    i have a comet in a 55l fish tank and a yellow goldfish how many fish would i be able to have in there i don’t have the room for a larger fish tank but want to get them 1/2 new friends to go with them .

    Rating: 5
  34. Lesley Parker April 13, 2019 at 11:59 pm - Reply

    Interesting that none of the flamers on other websites going on about cruelty, and 20 gallons per fish etc, has posted here. MAybe they are only comfortable criticising those who are inexperienced and feel they cannot fight back. Thanks for this. I ahve been wondering how big I need to have a small pond if I want 6 or 7 fish. Very useful info. (PS for those non-US remember it is 3.8 L to the US gallon as opposed 4.5L to the British gallon).

    Rating: 5
  35. Sandy April 14, 2019 at 6:07 pm - Reply

    Very informative. Thanks. I love Lionhead’s but have no room for a large tank. 10g is my limit.
    Could I get two small ones with a 25% water change each week ? Should I get a slightly oversized filter?

    Rating: 4.5
    • Pure Goldfish
      Pure Goldfish April 15, 2019 at 3:34 pm - Reply

      Depending on if you can keep your nitrate levels under 30ppm with your setup, go for it.

  36. carol jones April 15, 2019 at 5:49 pm - Reply

    Love your no nonsense approach to fish keeping.
    I bred my Wakin goldfish last year and kept the resulting fry in stock tank in garage. Now they are coming out of thier dormant state but predictably are still very small because of not being fed all winter because it was too cold.
    My question is, if I have Wakin fry this year can I realistically keep 10 fry in a 50 gallon stock tank in the house until they are 3” in size come next Spring? They will be fed small amounts 3 times a day.
    Thanks for any advise you can give.

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 16, 2019 at 4:22 pm - Reply

      Sounds fine to me. But with heavier feeding like that you might need to do more wc’s.

  37. Asha williams April 16, 2019 at 6:45 am - Reply

    I’m a teenager and have never had a fish before I’m planning on getting a oranda goldfish and I had a few questions 1, I can’t afford to get a large filtered tank so I was going for a 10 gallon unfiltered one how often would I need water changes? Also would you recommend me keep the fish alone or add another small fish for company?

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 16, 2019 at 4:23 pm - Reply

      Depends on your water test results. Nitrates should never go above 30ppm. It depends on how large your fish will be, if its larger a snail would be a better option.

  38. Lindsay April 19, 2019 at 2:44 pm - Reply

    Hi! I have a fantail goldfish ( about 2”) in a five gallon tank and want to know if i can get another so she’s not bored? i’m going to upgrade her to a 29g with an apple snail, two cherry shrimp, 6 rosy red minnows and 7 blood fin tetras in hopefully around october 🙂 i just want to know if two fancies is two many for those sizes?
    Thank you!

    Rating: 5
  39. Lindsay April 19, 2019 at 2:46 pm - Reply

    I also forgo the to mention this is the first time i’ve had a fancy in an actual tank so i don’t know too much stuff about that 🙂 Thanks again!

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 19, 2019 at 3:59 pm - Reply

      29 gallons is more than enough for 2 fancies 🙂

  40. Lindsay April 19, 2019 at 5:15 pm - Reply

    is it ok for them to stay in a five gallon tank for six-eight months or is it too small for them? also, would they be ok with all those other fish with them?
    Thank you again! You are really helpful 🙂

    Rating: 5
  41. Lindsay April 19, 2019 at 5:45 pm - Reply

    also, if it is ok to have two fancies in a five gallon, do you have any recommendations for where to get one? the pet store closest to me doesn’t take very good care of their goldies and i want to get a healthy one 🙂

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 22, 2019 at 3:16 pm - Reply

      Just keep the water good until you upgrade 🙂 You can check online for breeders who will ship to you.

  42. Peyton April 21, 2019 at 11:58 pm - Reply

    Hi! I have 4 fancies in a 60 gallon tank. I TOTALLY agree with this article: I think there’s a happy medium between giving your goldies a healthy life and drilling people about their tank sizes. Not everyone can afford huge tanks for their goldfish, and it can turn away a lot of new goldfish keepers. THANK YOU for writing this, this article is one of the only sources that hasn’t been overly cautious about tank sizes! The way I see it, bigger is always better, but if you can’t afford a huge tank for your fish, they can still be perfectly happy! 🙂

    Rating: 5
    • Pure Goldfish
      Pure Goldfish April 22, 2019 at 3:20 pm - Reply

      Thank you, Peyton, I agree 🙂

  43. Lindsay April 22, 2019 at 6:01 pm - Reply

    can i use ducked tape to seal a really thin crack in on one of my tanks? it’s empty so there’s no draining needed. silicon takes a long time to dry so is there something else i can use that will last around two months? i hope you can help 🙂 it’s 3-4 gallons i think? it’s a little smaller than my five gallon. i just want to repair the crack fast so i don’t have to throw it out 🙁 thanks!

    • Pure Goldfish
      Pure Goldfish April 22, 2019 at 7:38 pm - Reply

      I don’t think that will be waterproof but you can try

  44. Joan April 22, 2019 at 6:31 pm - Reply

    For 20+ years I have had ‘rescue feeder goldfish’, in an outside 12″ deep x 22″ wide circular ceramic garden pot. Don’t have room for inside tanks. There is a water plant in it and a filter with a small fountain. There are 4 of them and they were 1-1/2″ at rescue and are now 3″-4″. No special care of the water, algae growing a bit on the sides, which they control. I feed them when I remember (they do know me), net the waste from the bottom and put it in my plants and top off the water as it evaporates. They seem to be content, nibbling on the algae, the plant, chasing each other for whatever reason. The oldest is 20 years old, that’s about their lifespan, which I feel is pretty good. These fish are very hardy, based on my experience. They are outside in every kind of weather (Mid-Calif.). Perhaps when fish are inside they need all of that stuff people buy for them, but I’ve found that they are very adaptable outside. While your article is extremely informative, I’m glad I didn’t read it all those years ago or I wouldn’t have any fish. Budgetwise, my way is best for me and my friends (seniors) have decided they are the best pets to have.

    Rating: 4.5

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