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

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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.

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.

In addition to these reasons, fatty deposits in the liver, kidney cysts and egg binding can also affect the bladder and lead to buoyancy issues.

In some fish, low water temperatures can enlarge the gastrointestinal tract by slowing down digestion. Just as the aforementioned reasons, this also puts the swim bladder under pressure.

Sometimes after eating too much a 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.

You should treat it accordingly after you estimate the nature of the problem, ideally through your local veterinarian.

How to treat the different conditions that cause your fish to swim upside down?

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 a manifestation of a swim bladder disorder that’s relatively rare. Fortunately, it is the easiest to treat. Constipation will cause a bloated stomach, which in turn will press against the swim bladder.

A good approach would be to offer your pet fish 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 omnivorous or herbivorous fish such as goldfish and the like:

  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 Amazon or 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 fish’s 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 to take 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 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.

#7. Fast the fish for a few days

This could be a good course of action if you’ve confirmed through a vet that your fish is constipated or has something that does not pass in its stomach.

If the swim bladder disease is caused by an enlargement of the gastrointestinal tract, then you you’d want to start the treatment by putting your fish on a three day fast.

The lack of food will prevent any further blockages of the intestines and stomach.

Meanwhile, you’d want to increase the temperature of the water to 78 – 80°F and leave it at this temperature until the end of the treatment.

This will relax the intestines and reduce the swelling.

Finally, if you’re fish is carnivorous, such as a Betta, you’d want to give it a few pieces of frozen, freeze-dried or live daphnia during the fast.

The daphnia will act as a laxative that will push out any food matter that may be blocking the gastrointestinal tract.

Author’s note: A short fasting is the easiest course of action when your fish is having constipation issues. However, from what I’ve seen, constipation is rarely the cause for upside-down swimming in pet fish.

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. This makes you responsible for the amount of food they will consume each meal. 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 Amazon).

    Anyway, another outcome of overfeeding is water contamination.

    Leftover food will quickly break down into ammonia, overwhelming the aquarium’s beneficial biofilter of 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.

My Conclusion

Swim bladder disease is a tricky condition to treat and I’ve personally fought it numerous times. In my opinion, the key to success is reacting in time.

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.

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

  1. hey, i have i gold fish and it’s been going upside down a few times. swimming slowly. normally a lil playful. i have helped it twice. today the third time. i tried the pea trick and i do help it swim around. helping it swim around it got back to its routine for a lil bit. is there a possibility of something else? to help it

  2. I have a large older pond fish that has been floating upside down for a week. It is alive and will swim when approached. It is winter here. The pond has a small heater and air bubblers. There are 8 other goldfish in this pond all are ok. I tried feeding it a pea but it won’t eat it. Is there anything I can do for this fish?

  3. I have a hospital tank. Is it enough to treat the water with the antibiotic or do I need to mix it into the food as well? I did both for a week and he got better but now he is sick again. Was thinking I needed to medicate longer however medicating the the food and getting him to eat it is very difficult so wondering if I can just treat the water ? Thanks!

    • Hello,

      Treating the water is enough. The water enters the fish’s body through its gills.

      Good luck!

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