Why Goldfish Is Floating Upside Down?

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Have you noticed your goldfish behaving weirdly recently? If your goldfish suddenly appears to be swimming upside-down, side-ways, or with its head tilted down, you might be dealing with a case of a swim bladder disorder. Don’t worry though!

It might sound serious, but most often, this condition is not life-threatening. With proper care and a bit of extra attention, you can nurse your goldfish back to health. Keep reading to learn more about this disorder, and the best ways to treat it!

What is Swim Bladder Disorder?

Swim bladder disorder, also known as swim bladder disease, or flip over, is a widespread problem in aquarium fish, especially goldfish.

Despite its name, this affliction isn’t one single “disorder” but a syndrome that can have multiple causes.

This syndrome appears when the fish’s swim bladder is affected, primarily when it is overfilled with air. This manifests in buoyancy issues. Typically, a fish with swim bladder disorder will float upside down.

The fish might also sink to the bottom or float to the top of the tank, depending on the cause of the issue.

The swim bladder is a very delicate organ. It looks like a small, elongated balloon and it has a very thin membrane. It needs to be able to tightly regulate the content of oxygen and gases in a fish’s body.

It’s thanks to this special organ that fish can effortlessly maintain buoyancy and proper upright posture in the water. As you can see, any small malfunction can lead to swimming troubles.

Sadly, goldfish are most susceptible to this syndrome. Goldfish are classified as physostomes. This means that their swim bladder is directly connected to their mouth.

They can quickly fill up with oxygen by gulping air at the surface. When goldfish feed at the surface, they can gulp up too much air, overfilling their swim bladder.

Causes of Swim Bladder Disorder in Goldfish

As I’ve already stated, there are multiple possible causes for this disorder. Some are easier to solve, while others will require medication. I’ve already mentioned gulping while eating. This leads to an overly-distended swim bladder. Feeding your goldfish floating flakes and other similar foods might be the first culprit.

Switch to sinking foods. Whatever you do, keep your goldfish from feeding at the surface. The second most common cause is a displaced swim bladder, most commonly due to a distended stomach.

Sometimes, a goldfish’s belly can get so swollen that the swim bladder is pushed and squished up into its body. You can probably see how this can affect buoyancy regulation.

A distended stomach can happen due to multiple reasons, most of them related to feeding. Your goldfish might be eating too quickly. Some of that air they gulp could also end up in the stomach, contributing to the expanded belly.

You might also be feeding your goldfish too much. If you rely on flake foods or freeze-dried foods, know that these can expand a lot once they absorb more water.

What looks like a little bit, might later expand in the goldfish’s belly and intestines. Perhaps your goldfish are constipated. This can also cause distension in the intestine, which leads to further compression of the swim bladder.

A low-fiber diet is the most common cause of constipation. Constipation can also arise from exposure to high nitrate levels.

Monitor the water quality to ensure that all parameters are within the optimal range. Less common causes include bacterial infections, intestinal parasites, or fluid being trapped in the swim bladder.

If the dietary intervention doesn’t work, you should quarantine your fish and start treating it for parasites.

Treating Goldfish Swim Bladder Disorder

The way you treat swim bladder disorder will differ slightly, depending on the cause. If you can’t exactly tell what the cause is, I suggest following the next steps and stopping when you see a reversal in the symptoms.

These steps cover everything from air gulping and constipation, all the way to parasitic infection. By the end of this short guide, no stone will be left unturned. Here are the steps:

Step 1: Check and maintain the water parameters. Changes in temperature, pH, and nitrate levels can all lead to digestive issues and concomitant swim bladder disorder. The most important thing you can do for the short- and long-term health of your goldfish is to maintain pristine water at all times.

Make sure that everything is within the suitable range. If you don’t already, regularly cleaning your filter media with aquarium water will maintain the best performance. You might also have to perform larger water changes, around 30% once a week.

Step 2: Let the goldfish fast for three days. If your goldfish is overstuffed or constipated, adding more food on top of that won’t help. Allowing them some time to process and eliminate all that matter should solve the issue.

And don’t worry, goldfish can go for as long as 2 weeks without food. A short 3-day fast won’t do any harm. They just need enough time for the food to complete the transit before leaving their body.

Step 3: Give your goldfish a green boost. Boil and deshell some green peas. Feeding them cooked peas will increase their fiber content, which will speed up their intestinal transit. This should take care of constipation and distended intestines.

Step 4: Switch up their diet. This includes everything I’ve already mentioned earlier in this article. Make sure your goldfish receive a balanced diet that includes both protein and fiber-rich foods.

If you haven’t already, switch to sinking foods to prevent your goldfish from feeding at the surface, where they gulp too much air. Always pre-soak dried foods and flakes prior to feeding. This prevents the fish from eating too much at once because the food expands before feeding.

Step 5: Slowly raise the water temperature to 77-80°F. Goldfish are considered coldwater fish, and there are some advantages to a slightly colder tank. But great digestion isn’t one of them. Colder water will slow the fish’s metabolism and digestion, leading to constipation.

Step 6: Move the affected goldfish to a quarantine tank. If none of the steps has helped so far, the fish might indeed suffer from an infection. Separating the fish from the main tank will reduce the risk of further infections in tankmates. You also won’t be polluting the main tank with antibiotics and other medications.

Step 7: Look for signs of infection and prepare to apply antibiotics and anti-parasitic medication. When dietary changes fail, it’s time for a more in-depth approach. If your fish seem dull, lethargic, and they lack an appetite, these are clear signs that something more serious is going on.

You can find broad-spectrum antibiotics and more targeted medications like metronidazole, levamisole, or praziquantel in most pet shops, as well as online. You can also find specialized anti-bacterial swim bladder treatments such as those from NT Labs. Whichever treatment you choose, always follow product instructions as indicated on the package.

How to Prevent Swim Bladder Disease in Goldfish?

Here comes the good news! There’s nothing special you need to do to prevent further swim bladder disease. If you already made the necessary changes to treat your affected goldfish, you can just stick with that.

What cures swim bladder disorder also works to prevent it. To reiterate, here’s what you should do to treat and ward off the disease:

  • Maintain your tank in pristine conditions. Dirty water predisposes your fish to bacterial infections. It also leads to higher nitrate exposure. Both of these things can negatively impact digestion in goldfish.

You’ll have to perform larger or more frequent water changes, together with further cleaning. Don’t forget to siphon the gravel, unclog your filter sponges, and wipe down the aquarium walls regularly.

  • Bump up the temperature to 77-80°F. Coldwater, although suitable for goldfish, can have a negative effect on digestion. Warm water will increase the goldfish’s appetite and keep things moving.
  • Avoid overfeeding. Only give your goldfish as much as they can finish in up to 2 minutes. Feed them at regular intervals, no more than 3 times a day.
  • Feed them a proper diet. This includes high-quality foods and a combination of protein and veggies. The fiber-rich plant foods will prevent constipation in goldfish. Only choose sinking foods and always pre-soak dried feed beforehand.


Witnessing flipover in fish for the first time can be distressing. At first glance, it might appear that the fish is dead. It certainly doesn’t look comfortable.

Unfortunately, due to their anatomy, goldfish are susceptible to this disorder. Luckily in most cases, this is not a life-threatening condition.

If the root cause of the issue receives attention, the fish can make a full recovery. The two most common causes of swim bladder disorder are excess air in the swim bladder, or a displaced swim bladder (almost always due to a distended belly).

If you follow the steps outlined in this article, the issue should resolve in a matter of days.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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