Why Is My Goldfish Swimming Upside Down? – How to Fix The Problem

Ever found yourself asking the question: Why is my goldfish swimming upside down?

If you look in your tank only to see this, it doesn’t necessarily mean they’re dead, so don’t flush them just yet!

In fact, it’s fairly common for goldfish to end up floating and swimming upside down, but that doesn’t mean it’s normal behavior.
A goldfish swimming upside down isolated on white

Buoyancy problems such as swimming sideways or upside down in their tank is a sure sign that there’s something up with your goldfish. This article is going to shed some light on what’s happening and what you can do about it.

There are few possible reasons, nearly all are down to poor health, but the good news is, it’s pretty much always curable too.

Why is My Goldfish Swimming Upside Down? What is the Most Likely Reason?

If your goldfish is swimming upside down, the most probable cause is swim bladder disease or disorder. Despite the name it really isn’t a disease, it’s a symptom of one of several issues that could be affecting your goldfish’s swim bladder.

The swim bladder is a gas-filled internal organ that fish use to regulate their buoyancy and move up and down normally in water.

So, when something’s affecting it, it can cause a fish to float upside down or on swimming on its side, which are unmissable symptoms of swim bladder disorder.

What Might Have Caused it to Happen?

Fancy goldfish are prone to issues with their swim bladders, especially those varieties that have been bred to have bulbous or balloon-like bodies, like most fancy varieties.

That said, there’s still always a reason behind SBD, so let’s look at some of the possible causes:

  • Constipation. Feeding a poor-quality diet or too large a meal can cause your goldfish to become constipated, and the blockage can temporarily stop the fish from being able to regulate their swim bladder.
  • Swallowing air. If you feed your goldfish flakes or other foods that float on the surface of the tank, they may ingest a large amount of air when they eat, which can cause issues with their swim bladder.
  • Food expanding in the stomach. Certain types of dry pellets and freeze-dried food expand when moist, so if your fish eats it as soon as it hits the tank, it can expand in their stomach, which stops them from being able to properly regular their swim bladder.
  • Bacterial infection. Sometimes SBD can be a symptom of an underlying bacterial infection.
  • Changes in water temperature. Certain varieties of goldfish – such as round-bodied varieties – are susceptible to sudden changes in water temperature.
  • Large amounts of nitrate in the water. Some fish keepers have found their goldfish react badly to having high levels of nitrate in their aquarium water.

Should I Be Worried About My Goldfish Floating Upside Down?

Usually, swim bladder disorder is simply caused by eating too much food or ingesting air with the food, and should fix itself with a few days of fasting your fish.

However, if your fish also looks unwell – for instance, is lethargic and has legions or discolored scales – it may be the sign of a bacterial infection. In which case, you should be more concerned, and it may warrant a trip to the vet.

What Can I Do to Treat the Problem?

The treatment for swim bladder disease depends on the cause.

If the issue is down to water quality – too high nitrates – then the cure can be simple! Make sure you improve on the water quality care for your fish tank. Start with a large water change, clean the substrate of any waste and uneaten food, and then make sure to perform ongoing monitoring of key factors using a water quality testing kit. Ensure all parameters are within safe levels.

If the problem is down to constipation – which is very common – the first thing you should do is to ‘fast’ your goldfish for 3 days. This means do not feed them at all for 3 days, to give their digestive system time to clean itself out completely.

Next, you should feed your goldfish cooked and shelled peas at a rate of about 2 to 3 per day, which is a known way to relieve constipation issues. Then move them back onto a species specific diet.

However, if the swim bladder disease is due to a bacterial infection, is a genetic defect or the swim bladder has some form of permanent injury, feeding peas will not have any effect, this is only for constipation related issues.

If after fasting and feeding peas, the issue persists, you can rule out digestive issues and then have to try cures for alternative causes, as specified in this article by TheSprucePets,  a guide on the different ways to treat it.

Can Swim Bladder Disease be Cured?

Sometimes it can, yes. Though sadly it can be permanent.

Usually it’s just an issue with the digestive system that affects the swim bladder. So as suggested above, a few fasting days, followed by feeding skinned peas will alleviate the problem. However, if it’s due to permanent swim bladder damage, or genetic in nature, there may not be a cure.

Is Swim Bladder Disorder Fatal?

Unfortunately it can be, but also some fish can live many years with the problem. It depends on the cause and the severity.

Mostly, if the issue is down to digestive issues, or bacterial infection, it can be treated and will clear up. However, if the infection leaves lasting damage, or if the SBD is down to a genetic defect, it’s not curable and may be present for the rest of the fishes life.

Even if permanent though, it’s not necessarily fatal. Most fish seem able to cope with it, can right themselves often enough to be able to feed and perform natural behaviors, so SBD isn’t fat in of itself.

How a Vet Can Help

In some cases, it might be best to speak to a vet who specializes in fish to treat the problem. Take a look at this video from Dr. Loh fish veterinarian to see what a qualified vet can do to treat SBD. Obviously, you shouldn’t be trying this yourself at home.


Is There a Way to Prevent Swim Bladder Disease?

The best way to deal with swim bladder disorder is with a pre-emptive strike. Here are some ways you can lessen the chance of it ever developing.

  • Feed foods that sink to the bottom of the tank rather than floating on the top.
  • Avoid feeding dried pellets or freeze-dried foods unless you soak them before putting them into the tank.
  • Don’t overfeed your goldfish.
  • Make sure the water in your tank is kept at a stable temperature.
  • Check the water parameters in your tank to make sure it’s not too high in nitrates or any other undesirable substances.


Most goldfish found swimming upside down are suffering from some form of SBD. On its own, it isn’t necessarily too serious, but it can be a sign of a more problematic underlying issue.

In many cases, swim bladder issues will go away on their own or can be dealt with at home. But, if in doubt, it’s wise to seek advice from a veterinarian who’s experienced in working with aquatic creatures.

Happy fish keeping!

Wendy Kathryn

Hi, I'm Wendy, the owner and creator of this website, an experienced fish keeper and avid student of the art since 2010. My aim is to help beginners avoid the many possible mistakes when getting started in this wonderful hobby.

31 thoughts on “Why Is My Goldfish Swimming Upside Down? – How to Fix The Problem”

  1. Avatar

    My fish, jaws is floating on his back a lot and he has loss of color and so I’m really worried about him. I just wanna know if he’s ok.

    • Wendy Kathryn
      Wendy Kathryn

      Hi Kai,

      I’m sorry to hear this 🙁 Floating on his back is certainly not normal. Follow the advice in the above guide, and if that doesn’t help then I can only suggest trying to seek out the advice of a local professional who can come see your fish and try to diagnose more accurately what may be happening.

    • Avatar

      My fish suffered ammonia poisoning, I took care of it and he looked so much better but then started to swim on his side. I just introduced pellets that swelled up before they ate it. Is it that? Or did some bacteria from the ammonia poisoning cause this? Please help, thanks.

      • Wendy Kathryn
        Wendy Kathryn

        Impossible for me to say I’m afraid. I can say though, please make sure when feeding pellets that swell, that you soak them in some tank water for a couple of minutes before adding to the tank, so they are swollen before being eaten, and do not swell in the stomach.

  2. Avatar
    Mandy louise Cockayne

    hi, I,ve moved my gold fish from my old pond and put it into a new pond, the new pond has been up and running for a month, water conditions are spot on, but after a couple of days the fish start floating on there sides and struggling, l put them back in the old pond next day there fine, this has happened twice,why? thanks

    • Wendy Kathryn
      Wendy Kathryn

      Hi Mandy,

      It’s really hard to know to be honest. What water parameters are you measuring? Is it possible something has or is leeching into the new pond? Chemical run off from surrounding area such as fertilizer, pesticide, anything like that? Is the water oxygenated enough?

  3. Avatar

    Hi, our goldfish has been floating on his back now for about 4 months. However, when we go over to the tank he gets excited and flips over normally and swims up to the glass. The last few days he has found it more difficult to roll over and to get food so I’ve had to roll him over with my hand and move him around to the food and hold him until he’s managed to eat some. We have 3 others sharing the tank that have not been affected at all. Is there anything you can suggest to help him? The 4 of them have been in the tank for 2 years now without any other concerns at all.

    • Wendy Kathryn
      Wendy Kathryn

      Hi Lee. Have you tested all water parameters to make sure there’s no issues there? Also, try fasting him for a day, and then feed only sheeled peas so you clean him out and see if it’s anything digestive system related.

      What type of goldfish is he? A fancy, round bodied type?

  4. Avatar

    My small goldfish is still alive and will swim to the bottom rapidly when I tap on the bowl. But after eating, he looks bloated and struggles to not float to the top. Often he is floating upside down but still breathing, just not moving much. I do feed the flake floating food and there are 3 other larger fish in the bowl. I don’t know what kind of food to feed him or if I should remove him from the big bowl and have him fast for awhile??

    • Wendy Kathryn
      Wendy Kathryn

      Hi Deb,

      We cna never be sure, but there’s a chance he is gulping down air as he is eating the flakes from the surface, which can often result in what you describe. Try to feed some ‘slow sinking pellets’, so as you put them into te tank, they slowly fall down and they eat from mid water and the bottom. Soak the pellets first in a small amount of tank water so they start to sink as soon as you put them in. See if this helps at all…only a theory, but worth trying.

  5. Avatar

    I Hi ). I had a goldfish who was fine and then started swimming upside down one day and the next day they were just dead, they weren’t moving or anything, just dead. I’m sorry I don’t really know how to phrase it any better, I just wanted to know why my goldfish died. It makes me feel like i’d Done something wrong, and I want to know what to d next time if this happens again to my other goldfish.

    • Wendy Kathryn
      Wendy Kathryn

      Hi Astra,

      It’s impossible to say from the description alone. Something as abrupt as this may have been disease, or a blocked disgestive system, or some sort of poisoning (if anything fell into the water?) but it really is impossible to know. If it was down to water parameters running away, there’s usually a good amount of time passes, seeing their health decline and a good amount of time to turn it around (days at least!), and this sounds too abrupt for that. Of course, you haven’t mentioned their age, maybe it was just their time? I really cannot say.

      I would recommend just swotting up on correct goldfish care, make sure you set up the tank optimally for them, learn about correct diet and so on, and then go for it again. You’ve likely just been unlucky and – fingers crossed – things will be fine with new fish. I recommend going through our complete guide to goldfish care here: The ultimate guide to goldfish care.

      Best of luck!

  6. Avatar

    Hi we changed my sons round fancy goldfish from one tank to another without a heater as he ate one of the samaller fish. He is curently swimming upside down but is breathing. Ive returned him to the previous tank with the heater as i think the temperature change might have affected him. Is there anything i can do. My son is heartbroken and i feel terrible.

    • Wendy Kathryn
      Wendy Kathryn

      Hi Peter,

      Sorry for the late response, I’ve been away for a while and not able to respond to messages. A sudden change in temperature can lead to a lot of stress and then illness, but it could also be SBD. Did you check out the aquadaily article linked to above for advice?

  7. Avatar

    My small black gold fish is just moving round and round (want to go fast but just turn to right side). looks healthy no other issues. Pls help

  8. Avatar

    Sorry but I’m new to taking care of goldfishes. So the fishes have been with me for only a month, the others seem to be perfectly fine but this one goldfish is upside down. Even when I try to turn it, it just goes back upside down. It also has a bit of red on its gills(or whatever it’s called) not the fins, the gills.
    And it also just floats on top of the tank. I know it’s alive because it can still move and swim on top of the tank.

  9. Avatar

    I have had a generic goldfish for 6years, just in a bowl no fancy filters, small pinch of flake food once daily, cleaned weekly. I did contemplate purchasesing such things but he lasted so long and he’s been very happy i didn’t bother. I have recently changed and bought new stones for the bowl. I have come home today to find him on his side not moving much, he will wriggle and go upright when the bowl is moved but mostly stays still on his side. Because i don’t have an aquarium type set up i don’t know what advice to follow. I have made sure he has new water but can you help save him? It has been 6 years and i am very attached to him

  10. Avatar

    Hi,I have just noticed something sticking out of my goldfishes Gill so I removed it ,the fish went mad swimming around for a while but two days later he is swimming slowly in circles on his side is anything wrong with him or is he just recovering?

    • Wendy Kathryn
      Wendy Kathryn

      I’m not sure anybody will be able to help without detailed close up photos of what was in the gills? Sorry.

  11. Avatar
    Pratap singh

    Please help me out .
    My goldfish is floating upside down and his stomach seems to have become little bit big in size .so i moved him out from tank and puted in bucket.

    What should i do now ???????????

  12. Avatar
    Taylor mchoul

    How do I treat my goldfish with a swim bladder problem please and what do I give it to sort this out thanks

  13. Avatar

    My Goldfish has been upside down and not moving much for the last 2 or 3 months,
    We tried asking our friend and family but they couldn’t help, I don’t know any vets around, I came home one day to see a red spot near its gills.

    Please help Us

  14. Avatar
    Larissa Ranz

    We just bought an upside down catfish that is well…swimming right side up and can’t seem to swim straight. He flops all around and somersaults through the tank. It makes me tired just watching how much energy he is using flipping and flopping around! Since he is supposed to be upside down and isn’t really spending much time that way would it be a good assumption to think he has a swim bladder issue?

    • Wendy Kathryn
      Wendy Kathryn

      Hi Larissa,

      I don’t know much at all about the upside down catfish.

      Can anybody else reading this help?

  15. Avatar

    My goldfish was floating sideways and his stomach was little bit big in size .I moved him in a small tank 1.5 gallons with a 10L filter immediately raised the temperature to 80 degree. He recovered next day morning around 70 %. By evening he recovered 100%.

    I didn’t feed him for a day and he was just fine. After recovery i fed him little bit

  16. Avatar

    Hi! My goldfish is having a problem where they are not going to the bottom of the tank and poking a the rocks (like they normally do) and is instead staying in the middle-ish area and floating to the top a lot. And sometimes when they go to the top they flip to the side and then tilt back quickly.
    What do you think this is? I looked at an example of a fish that has SDB and mine seems to be behaving the same way. Should I be concerned?

  17. Avatar

    I have a fancy goldfish that was floating on her back at the bottom of the tank but when I would tap on the glass she would swim around I read the article and thought maybe it was because I was feeding food at the top and was getting air in the belly. So I decided too fast her how long can they go without food and be okay ?

  18. Avatar

    Plsss help my goldfish is floating on its Back ang twirling round . She seems fine. No discolour or no problems breathing. Its a Young fantail. Water is all Good 😁Mango(my goldfish) Has been swimming funny since yesterday morning. She is eating fine .

  19. Avatar

    Hi my fish jumped out of its tank dont know how long it was there til I came home from work It wasnt breathing or moving and I put it in cold water but now its left fins not moving and it keeps turning upside down

  20. Avatar

    Hi I accidentally put my fish in warm water as I cleaned the tank and when I put it back it kept on floating upside down.

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