Fish Swimming Upside Down (Swim Bladder Disease)

Swim Bladder Disease

Nothing quite frightens a responsible fish owner like their beloved pet goldfish swimming upside down.  Just the sight of it is upsetting and the internet just makes matters far worse.

They dubbed it a disease and that is not quite accurate. Luckily for you, we are here to shed some light on certain things and assure you that your pet fish is doing just fine- for the most part.

When a fish swims belly up towards the top of the tank or at the bottom, its usually caused by a condition called “The Swim Bladder disease.” Although the name is quite misleading, the disease isn’t actually a disease or is it deadly.

It is a kind of buoyancy disorder and it is caused by a number of things like:

  • Constipation
  • Bacterial infection
  • Parasitical infection
  • Gulping air while feeding
  • Sudden temperature changes and;
  • Poor water quality.

A fish suffers from swim bladder disease when it loses control of its swim bladder. The swim bladder is the organ that controls buoyancy in certain fishes. It’s important to note that not all fishes have a swim bladder.

This disease is only common in pet fishes like goldfishes and koi. The condition causes the fish to take in too much air or too little and subsequently lose control of their ability to control their movements to a large extent. It also causes the expansion and contraction of the swim bladder, altering its pressure system.

In most cases the condition can be remedied, it just requires a lot of care, a change in feeding habits and sometimes a journey to the aquatic vet’s office. But in some rare cases, it might be uncurable and the fish might lead a slightly different life, but a full one nonetheless.

SBD or swim bladder disease isn’t really a disease, it’s more of a condition. On the off chance that your fish is one of those rare fishes that can’t be cured, there are numerous alternatives like weights and other accommodating stuff you can try. It’s really no big deal if you don’t mind a weirdly floating fish.

What is a Swim Bladder?

Before we go in depth and properly talk about SBD and how it can be treated, prevented and any other questions or concerns you might have about it, I feel like we should know more about the organ in question.

The swim bladder is an air bladder that is present in most bony fishes that allows them to easily ascend [swim upwards] and descends [ swim downwards] without expending energy.

This is achieved by taking in air from through the mouth [ particular to goldfishes and other physostomous fishes] or the blood vessels [ exclusive to physoclistous fishes] in particular quantities to control balance and movement.

Fishes that have swim bladders rely on it heavily to maintain balance at all times and when it is damaged or affected, they would usually start with a slight right, left upwards or downwards movement.

Like all conditions or disorders, it doesn’t occur overnight, it’s a slow process and left unchecked, it can be quite a problem.

Most times swim bladder disorder is caused by inflammation or mounting pressure

I think it’s important to establish that the overall size of the swim bladder is in flux when a fish suffers from SBD. SBD is primarily caused by mounting pressure on the bladder itself or increasing its oversize one way or the other.

For example, temperature changes can affect the size of intestinal organs around the bladder and this mounts pressure on the swim bladder distorting its natural dimensions and causing problems with buoyancy and balance.

Bacterial infection, as well as gulping in too much air, can distort the overall size of the bladder and also lead to SBD.

Swim Bladder Disease Symptoms 

There are quite a few positions believe it or not. The traditional belly up look isn’t the only way your fish can decide to swim when it been hit by SBD.

Sideways up: I think this is pretty self-explanatory. Its when the fish swims and floats sideways as it swims.

Tails up: This actually looks stranger than the rest. This occurs when the fish swims with its tail towards the top of the bowl or aquarium and its nose facing downwards.

Sticks to the bottom: This is when the fish just swims at the bottom of the tank and just stays there.

Belly up: This is the type of SBD movement is the most popular. It resembles the traditional position that a dead fish assumes but with the distinct difference of the fish in question being alive.

Gold Fish Swimming Upside Down

Causes of Swim Bladder Disease and Their Cure

Now that we have established that what the swim bladder is and what kind of fishes have them, we will go on to address the causes of this deformation and eventually suggest solutions that may prove useful to you.


Constipation happens when the stomach or intestines of the fish become bloated from overeating. It swells so largely it presses against the swim bladder and distorts its shape.

The compressed bladder is not in its accurate shape therefore, it cannot perform well. Like human beings, fish get bloated too. They need either a heavy diet of fiber or need to be starved until they appear to be fine again.

Starving your fish for a couple of days is not the worst thing. Most of them can go 48 hours without sustenance and was the exact amount of time we recommend if your little pet happened to be a goldfish. Regardless of the species of fish, the starving shouldn’t last more than 72 hours tops.

Another brilliant way to deal with constipation is feeding your fish only fiber for a couple of days. any source of fiber would do but I recommend peas.

  • Try to thaw them and cook them for just the right amount of time.
  • Gently peel off their upper layer and then soak it in water
  • After soaking it briefly, feed it to your constipated fish and skip feeding it for the next day or so
  • During this sensitive period try to change the bowl’s water as many times as you need to.

Swallowing too much air when they surface to eat food

During feeding time, a pet fish usually swims incredibly close to the surface to swallow floating flakes or food pellets.

During this time, they usually briefly surface as they swallow and for fishes that have their swim bladder connected to their mouth, they gulp in a little air with each swallow.

When they swallow too much air, their bladders swell up and their balance and buoyancy become uncontrollable. The most obvious way to treat for this is by changing the fish’s diet.

Changing the fish’s diet

This task might seem like a lot from the surface, but it requires little to no changes. firstly, you need to switch from flaky foods to non-flaky fish foods.

They may seem all that different, but upon a closer look, you’ll discover that the only difference is that one is better suited for certain fishes.

Choose a pellet-based food and soak it briefly in water to make sure that they sink instead of the float this time around. This will curb the feeding habit that is causing the imbalance and it should help your fish find balance again.

Bacterial infection

Detecting bacterial infection can be particularly tricky especially without an x-ray. Seeing your vet is the only to confirm that your beloved pet’s abnormality is caused by a bacterial infection.

Usually, an x-ray will reveal if there is liquid in its swim bladder immediately and from there the nature of the liquid will be determined and subsequently treated with the appropriate antibiotics.

Usually, in cases of bacterial infection, there are usually other signs that accompany the inappropriate swim patterns. They include loss of appetite, stiff fins, and constant shaking.

Natural deformity

In some rare cases, the swim bladder isn’t affected by environmental features, the problem is innate and far more complicated than your average case of mistake or negligence. The fish was just born that way and it is very little you can truly do about its condition.

In certain cases, fishes like the goldfish or the betta fish are born with malformed swim bladders and it radically affects the lives they lead.

No one really knows why goldfishes, in particular, are prone to this condition, but there are theories that it’s a byproduct of centuries of genetic selection to achieve its current aesthetic appeal.

A goldfish might swim on its side for no good reason and there really isn’t much you can do about it. Since the field isn’t widely explored, there is very little that can be done when your pet fish suffers from this deformity. However, it should lead a full life if you choose to keep it.

Physical damage

This is very unlikely, but it’s better to always cover all our bases. It is completely possible that your beloved betta or goldfish got physically damaged without you knowing.

Since fishes can be immensely fragile at times, it’s no surprise that the swim bladders could be damaged during transportation or some other form of altercation with a bigger fish perhaps.

When this happens, it’s untreatable. There is absolutely nothing that can be done for the fish. I know it sounds final and disheartening but it’s the truth. The only way to be of help in any way is finding ways to support the fish and help it live a long, happy life.

Poor State of the Aquarium

Most often than not, this is the go-to cause of SBD. When your aquarium water is in poorly taken care of, your fishes are bound to get really sick.

Goldfish in particular have displayed the innate tendency to easily develop this infection once exposed to the wrong conditions.

Most people don’t really know this but Goldfishes produce a lot of waste. Their waste production is far above the average aquarium fish and because of the enormous amount of waste they produce, its always much harder to look after them effectively.

For example, the waste of the average goldfish contains a significant amount of ammonia, which eventually turns to nitrite and nitrate. These compounds are poisonous to the average fish and also promote algal blooms, so it can be quite problematic.

Certain studied have shown that on some level SBD is connected to high amounts of nitrates. So, to prevent your fish from swimming tail up, a regularly scheduled water change is recommended.

If your fish is already swimming funny, change at least 40% of the tank water or just transfer the fish into a bigger tank. That way it’ll take longer before the fish completely mock up the water. Regular filter changes and the addition of some sea salt per gallon is recommended.

Sudden temperature changes

Temperature change can cause SBD by mounting pressure on the swim bladder by increasing or bloating up other organs. At low temperatures, metabolism slows down in all warm-blooded animals, which includes the average goldfish and betta fish in this situation.

The low temperature causes the overall size of intestinal organs to increase dramatically and mount pressure on the swim bladder, this causes SBD.

When there is a sudden shift in temperature, this can trigger this process and make your fish go tail up or belly up.

You should get everything under control by trying to control the tank temperature at all times. Try moving it whenever you foresee a sudden temperature spike.

fish swimming vertically

Preventing Swim Bladder Disease

Now that we’ve established all the hallmark causes and symptoms of the disease or disorder rather, we should focus on preventing it if we can. Here are a few tips to help you keep your fish swimming right and safe.

Keep the tank clean at all times

Nitrates of any quantity are dangerous to all fishes. Since it has been connected to SBD then it would be wise to keep the fishes as far away from it as much as you can.

This means changing the water at least once a week and scrubbing down the tank once a month.  During this little cleaning session, the filters and the graphite should be cleaned too.

Keep the water temperature at a cool

Keeping the tank at this temperature will ensure that there are no sudden temperature changes that might jeopardize the balance of your fish. Perhaps a thermostat or some heat control device of some kind can be used to maintain this uniform temperature.

Feed them moderately

I know the thought of not feeding your goldfish properly might seem like an impossible concept now but I’ll tell you something that’ll change your mind forever. Goldfishes don’t have stomachs.

They don’t have mechanisms that tell them to stop eating. They are ever hungry and will always eat if you feed them. it’s almost impossible not to accidentally overfeed them. what I would recommend is reducing the volume of feed you give them and reduce the frequency too, if it’s needed.

Feed them pellets and try to soak them first

Regardless of the fish food, you decide to go with, you should always soak them first. It ensures that the fishes don’t swim upwards and start pumping air into their swim bladders.

Will my fish correct itself after a water change?

That depends on whether the SBD in the first place. If it was caused by the nitrate filled water, then a water change and some rest should cure the fish of the disorder.

Do I need to change the content of the tank if my fish is permanently stuck swimming weird?

An adjustment is always expected after every major change. Your fish’s current state is a change that must be subsequently followed by certain alterations to the components and contents of the tank.

For example, if your fish swims nose down, then you should change the graphite to something softer and reduce filter current.

Aside from its inappropriately scary name, there is nothing distinctively terrifying about the Swim bladder disease. If anything, the disease- which isn’t actually a disease- is overhyped and in most cases is just a mild case of indigestion.

With adequate care and attention, any fish that isn’t injured or born with the deformity will have no trouble shaking it off.  Its non-life threatening and most people see it has a wake-up call.

It’s basically your fish telling you that you need to pay more attention to it. We have painstakingly combed through research and we are here to tell you that there is nothing to worry about. SBD is a mild scare at best.

Saurabh Kumar

I am a passionate fish keeper, with years of experience. You will find some really useful tips and information on this blog about Freshwater Aquariums.

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