Writing is hard work: when you order through links on my site, I may or may not earn a small commission.

Cause (+ Cures) for a Fish That’s Floating Upside-Down But is Still Alive?

fish floating upside down but still alive header

One day you wake up to the stunning sight of your favorite goldfish acting like a balloon.

A fish floating at top of the tank but not dead yet (even actively moving around) can be confusing to witness. What does that signal?

What about the other way around – your fish is swimming upside down but hangs out on the bottom?

In fact, this can happen to almost any fish species and not only goldfish.

Truth to be told if you find your little buddy swimming turned belly up, then its condition has probably been around for a while now.

The initial stage can be detected as soon as you notice sideways or even nose-down-tail-up swimming. Any form of imbalance in fish is to be considered a potential threat to its health.

Why is your fish hovering upside-down, but still seems alive and active?

If a fish displays such behavior it means that it has buoyancy issues. If that happens then you’d need to react on time and start treatment immediately. Here’s the reason behind a fish that floats upside-down, yet remains alive:

The impaired buoyancy in fish is caused by a malfunction of their swim bladder. When affected by Swim Bladder Disorder fish will often lose the ability to properly swim. They will float uncontrollably to the top of the aquarium, turned upside down, while still being alive. In some cases the fish will lay upside down or sideways on the bottom, unable to swim upwards. Affected fish will face difficulties when trying to maintain their floating balance, as the swim bladder is located in the lower half of the body.

The swim bladder disease in fish is not lethal on its own and it is rather a symptom than an independent condition.

Fish upside down

by vlcook

Note that in some fish such as the upside-down catfish swimming with the belly up is a normal trait of character.

What causes swim bladder disease?

A swim bladder malfunction is caused by a temporary or permanent deformation of the swim bladder. When it is deformed or narrowed in some way, the fish loses the ability to balance its body, while swimming.

The reasons behind that can be the pressure from a swollen belly, too much air swallowed, injury, or bacterial infection.

Sometimes after eating too much fish may gulp some air on purpose, to regulate its buoyancy.

To cure your fish you need to investigate the reason behind its bizarre behavior.

Treat accordingly after estimating the nature of the problem.

How to treat the different conditions that cause Swim bladder disorder?

Swim bladder disorder

by ExoS

Relocate your pet fish to a hospital tank immediately after noticing the odd behavior.

This way you’ll have way more control over the treatment without affecting other fish. All food or medication will go where it belongs – in your ill fish.

Sometimes the treatment requires days. Be sure to check the water parameters and maintain healthy water quality in the recovery tank.

That being said, here are the reasons behind swim bladder disorder and how to treat them:

#1. Treating constipation that results in a swim bladder malfunction

Swim bladder malfunction

by Training-Gap-5728

This is the most common manifestation of a swim bladder disorder. Fortunately, it is the easiest to treat. Constipation will cause a bloated stomach, which in turn will press against the swim bladder.

Many online sources advise that you should fast your fish to treat constipation.

However, a better approach would be to actually feed it. But you need to offer a specific food source – rich in fiber.

The fiber will force everything out of your fishes’ digestive system.

Here’s how to treat swim bladder disease caused by constipation in your fish:

  1. Thaw a frozen pea. It is better to leave the pea to thaw naturally. However, as this disease’s treatment can be time-sensitive I recommend microwaving it on the Defrost function.
  2. Boil the pea. Cook the pea in boiling water while being careful not to overcook it.
  3. Peel the skin off of the pea. The pea skin may cause swallowing complications for fish. You need the meaty insides of the pea for the treatment.
  4. Soak the pea in water. This is done to avoid swelling of the pea inside of the fishes’ stomach. Mind that the cooked pea will sink, so use a shallow container for the soaking.
  5. Feed your fish the cooked pea. Hand-feed the pea if needed. The fish will have difficulties getting the food. This is where the hospital tank comes in handy.
  6. Skip feeding in the next 24 hours. Let the fibers in the pea do their job at helping your fish with digestion.
  7. Clean off any leftover food after the offering. Hospital tanks are usually smaller. The water will quickly become dirty. A sudden ammonia spike, caused by rotting food is the last thing you’d want in a small tank.

This is the best-case scenario for constipation treatment.

The belly of the fish will lose volume, allowing for the swim bladder to function properly.

Another good source of fiber for treating constipation, especially for a carnivorous fish such as a Betta, is Daphnia.

At times Daphnia can be somewhat difficult to find in your local fish store, but you can find it over the better online stores for aquarium supplies such as Chewy (or just click this link).

Anyhow, sometimes the fish may also experience a loss of appetite.

In this case, you have no other option than to starve it. Fast the pet for 3 days.

Cold water slows down the metabolism of fish, which slows down digestion. Most fish will do well at a water temperature of between 72 and 80 °F (22 to 26.6 °C) during the fasting. This way the intestines will have the time needed to digest the hardened food.

On day 3 you should feed the cooked pea. Again, fast your fish for another 24 hours after that.

To avoid future bloating issues, you should diversify the fish’s diet. But more on that below.

Constipation may also be caused by food that’s swelling inside your fish’s tummy.

Monitor the fish’s stools: if they do not properly leave the body and hang from its rear for a couple of seconds, then that’s a clear sign of a constipated fish.

#2. Bacterial swim bladder treatment

Bacterial swim bladder

by King_Maoyu

How to kill bacteria in the swim bladder of your fish:

Sometimes swim bladder disease is caused by a bacterial infection.

This will result in the bladder being filled with fluid.

Sometimes, Swim Bladder Inflammation can occur with seasonality, research shows.

It can be estimated if the bladder holds liquid with ultrasound diagnosis.

If there’s liquid present the infection is either from spoiled water quality or bacteria.

The only certain way to confirm the cause is by a method called pneumocentesis.

Essentially, sticking a needle directly into the bladder and testing the fluid for the type of bacteria causing it.

With knowing who the offender is proper antibiotical treatment can be applied.

However, most aquarists, in their panic start treating the ill fish with numerous antibiotics.

If the issue doesn’t come from bacteria, but rather water quality, it’s strongly recommended for antibiotics to be avoided.

The misuse of antibiotics will cause more harm than good to a fishes’ immune system.

However, if you did measure the water parameters and are certain they’re not what’s causing the condition, using a broad-spectrum antibiotic is your best bet. Minocycline or Erythromycin are good examples.

Of course, your best course of action is taking the fish to the vet.

When an infection is present the fish will display other symptoms along with swimming upside-down.

There may be a loss of appetite, stiff fins, and uncontrollable shaking.

Note that to keep your fish safe from harmful bacteria and other pathogens you should consider getting a UV sterilizer.

#3. Bloating from swallowing too much air

Swallowing much air

by Paul Bradford

In a fish, there are actually two sacks acting as swim bladders. The larger one of them is directly connected to the stomach.

Whenever you feed non-sinking food you risk for greedy fish to gulp too much air while having their feeding frenzy. This may lead to a bloated swim bladder and therefore a disturbed buoyancy.

In this case, a boiled pea treatment will suffice.

#4. Birth deformation of the swim bladder

Birth deformation

by hweeheng

Sometimes, the reason for a malfunctioning swim bladder can be a birth deformity:

The swim bladder disorder is mostly seen in goldfish and bettas. Although a betta laying on its side could mean a number of things (click the link to see those explained), in goldfish it is not the case.

These two particular species have been continuously bred over time, to achieve aesthetic diversity.

The beautiful fish you see at fish stores today are the result of genetic selection.

However, with selective breeding come physical deformations.

This is why it’s so common to see these two species suffering from swim bladder issues (with goldfish holding the lead).

If a birth deformation is causing issues in your fish’s swim bladder there’s little that can be done.

You will need to apply special care, to ensure your fish leads a happy life.

Still, in time the condition will worsen and eventually turn lethal.

Often if the SBD is the result of a birth defect, symptoms are present at an early age.

An easier diagnosis is somewhat a relief because no further investigation is needed.

Another untreatable condition that will suppress the swim bladder is the development of tumors.

Your fish may have cysts growing its kidneys, which in turn will enlarge.

#5. Physical damage or injury

Physical damage

by ghooda

A high drop, engaging in a confrontation with other aggressive fish species or other mechanical damage can cause SBD:

If the swim bladder has been damaged by an injury, say, during transportation, there’s nothing you can do about it.

If your fish has just arrived and is being this way, without improvement from previous treatments then it is probably a goner.

Really sad, as these cases do happen on occasion and there’s nothing that can be done.

I recommend considering a humane way to euthanize it.

You will spare it the suffering from a slow and unpleasant death.

#6. Poor aquarium water quality (high nitrates)

Poor water quality

by isabelablue

Neglected water conditions may very well be the reason for an infected bladder:

As mentioned the disease is often found in goldfish. Aside from selective breeding, there is another reason for that.

Goldfish are known to make a mess in an aquarium. They poop way more than other fish of their size. Therefore they would need more gallons of water per fish than with others.

Unfortunately, this is often overlooked by new fishkeepers.

Significant amounts of waste will result in ammonia spikes.

The ammonia then converts to nitrites (NO2), which then become nitrates (NO3).

Research has shown that high levels of Nitrate in the aquarium can be related to swimming bladder infections.

Here’s a visual diagram from the research that shows the correlation between side swimming and high nitrate levels in the water:

In fact, if a fish has swim bladder issues, it’s a really strong sign that Nitrate poisoning is on the way.

Long-term exposure to nitrate levels of even 20 ppm (parts per million) can cause this.

Note that using a liquid water test kit is somewhat mandatory when accurately assessing the water’s parameters in your aquarium. Test strips can be quite off and only give a crude estimation of the actual Nitrate levels in the fish tank. Make sure to use a liquid test that has been proven to take accurate measurements. I can recommend using this or a similar one as it has done well by me so far.

Anyway, after constipation, nitrate intoxication is the second most common reason for sideways or upside-down swimming in fish.

To treat SBD in this scenario perform change up to 40% of the aquarium water over the course of a day, depending on the level of Nitrate. You’ll want to bring them down to about 15 ppm or less. To avoid causing further chemical shock to the fish only remove 5% to 10% of aquarium water per hour. Relocate the ill fish to a larger tank as soon as you can afford it.

If you can’t provide more gallons of water, then be consistent with the water changes or learn about ways to permanently keep the Nitrate at safe levels.

Nitrate-causing gunk can also build up in the aquarium’s filter, so change/rinse it as needed.

If your fish experiences upside-down swimming after a water change, this can be a good sign of environmental stress.

Sometimes after a huge water change that’s done at once (40% to 50%), the fish will start to breathe heavily and swim upside-down.

Even if it’s only one fish displaying the symptoms, it’s a strong confirmation of stress.

Removing too much nitrate ions from the aquarium water at once could impair a freshwater fish’s osmoregulation.

Osmoregulation is the ability of a fish to maintain osmotic pressure in its body fluids. An imbalance in that pressure could cause swollen organs and a malfunctioning swim bladder in aquarium fish.

Though nitrate is toxic in the long run, fish adapt to its presence to a degree. In the case of a nitrate poisoning event, you should remove the nitrates gradually to avoid further worsening the swim bladder condition.

Usually, in smaller tanks, there are not enough plants to control the nitrate levels, which can lead to an infected swim bladder.

Efficient ways to prevent swim bladder disorder in the first place?

Prevent swim bladder disorder

by BantamClear

Do these to ensure your fish would never have to face swim bladder disease again:

  • Avoid overfeeding. Providing your aquatic pets with too much food actually doubles the trouble:

    Fish do not recognize the concept of overeating. More often than not they will eat more than needed when offered.

    This may lead to a bloated belly, pressing against the swim bladder. One pinch a day should be more than enough for a small fish like a Betta.

    Related: How to Treat a Bloated Betta?

    To never worry about dosing food (and timing) you can just get an automatic fish feeder.

    One that really stands out is the Eheim automatic feeder unit. It works reliably and you will 100% not overfeed. Make sure you choose the right food, set it, and change the batteries every couple of months.

    That’s it.

    Oh, by the way, here’s a link to see the thing (at Chewy).

    Anyway, another outcome of overfeeding is water contamination.

    Leftover food will quickly break down into ammonia, overwhelming the aquarium’s beneficial bacteria. When this happens the fish tank will experience a nitrate spike that may lead to a swim bladder internal infection.

  • Avoid feeding floating foods. Pellets or other food that floats at the water surface encourages gulping air.

    Too much air in the belly of a fish can end up in its swim bladder. This will violate the balance and cause buoyancy issues.

    Feed sinking food if possible.

  • Avoid feeding air-filled foods. Some types of food will be more porous in texture than others. This introduces unwanted air in the fish’s stomach.

    The air from the stomach may get into the swim bladder and enlarge it.

  • Soak foods before offering. By soaking dried foods in water before offering you allow them to expand.

    This will prevent eventual expansion inside of your fish’s belly.

  • Thaw frozen foods. Whenever you offer a frozen meal, it should be fully thawed. These foods will gain volume when thawed.

    If this happens inside of your fish, it will lead to bloating.

  • Perform regular water changes. As much as this goes without saying, I am still obligated to mention it.

    Water changes will keep the nitrates in the aquarium in check, preventing potential bladder infections.

  • Buy a large filter. The bigger the filter – the more beneficial bacteria your fish tank is housing.

    The more bacteria, the stronger the biological filtration, lowering the chance of bladder infection.

    Canister filters are the most spacious so far. Here’s a list of those.

  • Maintain the water temperature. Fish are coldblooded creatures.

    This means that their metabolism is strongly dependent on their body’s temperature. Colder water will inevitably slow down their ability to digest food efficiently and on time.

    This can lead to constipation.

    If you have a small tank check my guide on some of the smallest and yet reliable fish tank heaters.

  • Diversify the diet of your fish. Once a week feed your fish high-fiber foods.

    It could be a pea or any other fiber-rich source of food your fish will be willing to eat.

    Another way to prevent SBD is by occasionally feeding your fish with bloodworm.

  • Avoid ball-like fish. The fancy goldfish is a good example. When stocking your tank avoid fish that are being bred to achieve a certain ball-like shape.

    In general, that’s most of today’s goldfish varieties.

Be mentally prepared for a grim ending

It is fairly important to point this out.

With swim bladder disorder there won’t be a happy ending every time. Usually, if the problem is caused by constipation the treatment is easy and efficient.

However, this is not always the case.

There are numerous factors that can cause this condition. A proper, yet timely diagnosis is not always possible.

Be prepared for everything.


Why are you still reading? Hurry up and help your fish buddy before it’s too late.

There’s always hope even though a fish turned upside-down usually signals the opposite.

Leave me a comment below if you need more answers.

Sharing is caring!

124 thoughts on “Cause (+ Cures) for a Fish That’s Floating Upside-Down But is Still Alive?”

  1. Hello,
    I have a guppy fish and ever since i done the first change of water it’s been on the floor and when it stops swimming if it rarely comes up it just sinks. i put some food in as i have other guppies which have not experienced this it started swimming then doing like spinning 360° as it swam then fell back down. I am worried as I thought it was trauma at first but it seems to be getting worse than better. it also has hung out by the heater out the back of the tank

    • Hey AJ,

      I think that you should check my article on how water changes can stress fish. Just go to the homepage of the website and find it there.

      It could also be trauma, but I think that when you read the article you’ll have more info than I do and make a better conclusion.

      Regards, Momchil

      • sadly when i woke up this morning my fish was still so it passed away. My other fish were still doing fine so I am not sure what the cause is, but he’s at peace now.
        Many thanks for your recommendation though.

        • Sorry to hear that AJ!

          I wish you better luck next time!

          You could dig into your water parameters and check what guppies require in detail (not saying you haven’t, but it could be something that you never thought could cause problems, like water hardness, etc).

          Stay well, AJ.

          – Momchil

  2. Hello,
    I have a goldfish that looks bloated and has been floating at the top of the aquarium for about two weeks now. I also have to hand feed her but she accepts the food readily.

    • Hi Andrene,

      To be able to help you, you need to tell me what from the above advice you tried and did not work.


  3. The pea saved my fish 🙂 it worked so quick too

    • Ha, glad I could help!

  4. HI All,
    I have an angelfish that has been listing and not acting herself for a week or so, and then in the last two days she’s been facedown with her mouth at gravel level breathing hard. We’d nudge her and she’d dart away and then summersault ending with her face down again. Now she barely moves and if you nudge her she attempts to right herself, only to end up face down again. I’ve done a partial water change and added some additional de-stressor but no changes. Help!

  5. Hi. We have bluegill in our tank. Just two I’m a 50 gallon tank. I noticed earlier this week that the smaller one had something eating the edges of her fins. Yesterday it was way worse. I took a sample of water to the local fish store. The nitrates and nitrites are off the chart high, and the ph is off. So we’ve got bad water. I put in two plants and put in a teaspoon of ph up. After I did the ph up my fish seemed to get gaspy. So I took out five gallons and added six gallons of filtered water, and began a pimafix treatment for the fungus on the fins. Now today my larger one is inverted. A different person helped me at the fish store today when I brought in another sample of water. She gave me prime conditioner but told me to hold off on this for another day or so since I just did the ph up and water swap. What do you suggest?

  6. Can symptoms happen suddenly? My goldfish was fine over the weekend and this morning. I left to do errands for a couple of hours and found her listless and dead looking, bent at her tail – everything!
    I’ve changed her water and given her a salt bath. She’s been on her side slightly bent still and occasionally fights to lie on her tummy.
    At times she breathes hard and sometimes she breathes slowly. She moves her eyes but mainly looks down. I’ve put peas in for her and she ate one but doesn’t ear the rest. I don’t have a hospital tank but shes an only fish. I’ve also put in Sachem Paraguard in her main tank, just one capful. (I’ve got a 20 gal. Tank)
    What else can I do??

    • Hi, Bel,

      Yes, that is possible. The curved spine signals either a Nitrate poisoning or a bacterial infection. What levels of Nitrate does the aquarium maintain normally? Above 20? If you think it may be Nitrate Poisoning, you may want to read my guide on the subject (use the search bar of my website).

      On the other hand, Paraguard will not treat a bacterial infection. Unfortunatelly, the one that may be causing a bent spine can be really difficult to treat, but you could try using Kanamycin. Also try to get your hand son Vitachem, as in some cases vitamin supplements help with the curved spine in fish.

      Keep me posted.

  7. I have a very small fish (think guppy size basically) that had been puffed up for 22 days straight. I starved it, I fed it peas, I changed water so many times, nothing. Well I thought there’s nothing else I can do, the only option is risk killing it by removing air with a needle or leave it how it is and just let things happen, whatever that means. So I did it. I accidentally removed too much air because the fish is so tiny that even the smallest amount of movement from the syringe was still too much but it’s surprisingly still alive. Problem is it’s still upside-down but now on the bottom of the tank. It ate, it pooped right in front of my eyes, it’s breathing normally it seems, it can swim around but upside-down and that’s it. It’s been 5 hours now. Idk it seems to be living fine even though upside-down. My question is… Is there a chance it can ever get back into a normal swimming position? Should I try and hold it right side up with a pair of tweezers or something for some time, in hopes it will somehow get… fixed?

    • HI Vic!

      Very bold move with the syrigne!

      The thing is that swim bladder issues may cayse bloat, but sometimes something else may cause bloat, resulting in a pressed swim bladder. There are one too many things that could cause the bloat. I have an article on bloated Betta fish, which applies to all fish actually, you may want to give it a read. I’m suspecting a bacterial kidney infection of some sort.

      Hope this helps…

  8. Goldfish turning upside down 5 days ago and hand feed him the peas, i started to put some Magnasalt to as describes in the box but nothing happened he is still upside down,what medicine will i have to put?

    • Hi,

      You could try an antibacterial fish medicine. Relocate the goldfish in a hospital tank and try treating a broad-spectrum antibiotic. Perform water changes every day, as the biofilter of the hospital tank will likely get wiped out by the medicine.

      But before you try all of that – how are the aquarium’s nitrates (in ppm)?


  9. Hi. We woke up this morning to find one of our goldfish wedged in a decoration. We got her out and ever since she floats on her side at the top. We have been holding her to help her stay straight. Every once in a while she will regain energy and swims around for about half an hour then gets tired again. We are going to try the pea method. Is it ok to just let her lay on top of the water like that? I feel bad just leaving her there.

    • Hi Kerri,

      Yes, it is okay to leave it like that.

      The fish may feel a little confused but that’s about it.

      Treating the underlying cause should be your top priority now.

      Good luck!!!

    • Kerri, take the decoration out. My dwarf goldfish has been doing the same thing for about 2 months. He could swim to the top and sideways but most of time he’d lay upside down on the bottom of the tank and look dead. I’d nudge him at least twice a day to make sure was ok. We’ve had him from an egg that the mana layed for 9 years and it broke my heart to see him like this. Yesterday I saw him half in and half out of a stump decoration and discovered he had passed away. He got half in the decoration, which was a big hole, but because he couldn’t swim normally he was unable to back up or go forward. I did cry when I found him and felt so bad I didn’t think to remove obstacles ahead of time so that’s why I say don’t take the change and just take all decorations out that might hurt him for now. Hope your little on gets better.

      • Debbie,

        So sorry to hear about your loss.

        I can only imagine your pain.

        When I saw your comment I immediately went ahead and checked our previous discussions to make sure that I’ve replied to you and have tried my best to help with what I can.

        Apologies if my advice was not useful to you, really! When I write blog posts I try to be as helpful as I could to the best of my knowledge, experience, and research.

        Sorry again for your loss, friend 🙁

        • Thank you so much. I really appreciate the help and suggestions you had to offer. It was all good but unfortunately I do believe his final demise was mostly the tumors. Your advice was wonderful and please do not think anything you said or didn’t say had anything to do with it. Please keep up your blog as it is very helpful and comforting to have someone to go to. Thanks again

  10. My goldfish is very bloated and is swimming along the bottom of the tank with her belly grazing over the rocks. She periodically swims to the corner of the tank and flips over on her back and stays like this for sometime. I took her to the emergency today, they gave her an antibiotic and said they could not properly diagnose without an X-ray. Should they have tested for sbd while she was in for an examination, especially since the symptoms are in line with this disorder?! I’m sad and confused😢To take her back to Emergency again tomorrow is 200$ to walk through the door before they even do any work.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.