Why Is My Guppy Swimming Upside Down? (Explained)

I have been keeping and breeding guppies for over 30 years, and in that time I have had my fair share of guppies that ended up swimming upside down in the water. The reason guppies end up swimming upside down almost always relates to a problem with their swim bladder, which is the organ that helps the fish swim and stays buoyant in the water.

Eating Daphnia
Eating Daphnia

Guppies have long been popular in our hobby. Since the late 1960’s hobbyists have been keeping guppies and selectively breeding them into the wonderful selection of colors on the market today. Guppies are easy-going, colorful, and hardy. However, even a fish as hardy as a guppy does occasionally become unwell.

What Is A Guppy’s Swim Bladder?

A guppy’s swim bladder is a gas-filled organ that allows the guppy to stay buoyant in the water without having to waste energy constantly swimming. The swim bladder is located above the guppy’s stomach.


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What Is Swim Bladder Disorder?

Swim bladder disorder is the name given to the problem whereby the guppy’s swim bladder no longer performs as it should. There are a number of potential causes of swim bladder disorder and these include;

  • Environmental issues (such as low water temperature)
  • Parasites or bacterial infections
  • Other organs becoming enlarged
  • Injury from another fish

Environmental issues (such as low water temperature)

Water temperature has an impact on guppy food digestion.

If the temperature of our guppy tank is consistently too low, our guppies may struggle to digest their food. This undigested food can start to release gases in the guppy’s stomach as it decomposes, causing the stomach to enlarge. As the stomach becomes enlarged it can actually move the swim bladder.

Unfortunately, once a guppy’s swim bladder has moved, there is little chance it will go back, even after the stomach returns to its normal size.



Parasites or bacterial infections

Parasites or bacterial infections can cause the swim bladder, or other internal organs to become enlarged or inflamed. As mentioned above, once the swim bladder moves due to other organs increase in size, even if it only moves a little bit, it usually won’t move back, meaning the damage is permanent.

Other organs becoming enlarged

Occasionally, other organs may become enlarged either through the growth of cysts or tumors, fatty deposits (especially around the liver), or becoming egg-bound (in the case of females).

Sometimes, a female guppy can have so many babies developing inside her that as a result, the swim bladder moves. Again, this move is usually permanent.

Injury from another fish

Although less common in small fish like guppies, it is well known that some predator fish will ram their potential prey with the aim of damaging or puncturing the swim bladder. Once the swim bladder is punctured, there is no hope of the prey fish swimming away.

Treating Swim Bladder Disorder

Treating swim bladder disorder can be very tricky, especially if the cause of the disorder is not known. In my experience, there is a setlist of things to try to see if the issue can be rectified.

If the issue is food-related

If you believe your guppy’s swim bladder issue may be due to undigested food, take the following action.

  • Stop feeding your guppy. Do not feed for the next 3 or 4 days
  • Increase the water temperature to about 82°F (28°C). This increase in temperature should help pass the undigested food.
  • On day 5, feed your guppy some live or frozen daphnia or brine shrimp. Both act as a laxative, helping your guppy’s digestion. (more on feeding guppies in this article I wrote recently titled What is the best food for guppies?)

If the issue is parasite related

If you believe your guppy’s swim bladder disorder may be caused by internal parasites, try a course of ParaCleanse by Fritz. ParaCleanse has been developed to help rid fish of internal parasites, including tapeworms (I usually order this one from Amazon). Follow the manufacturer’s instructions and see if your guppy’s swim bladder rectifies itself.

Other Options

Sometimes, none of the above will work, or if they do, the damage is already done to the swim bladder, and the fish won’t be able to swim correctly again. We can try a few things to help make your guppy’s life a little more comfortable.

  • Reduce the flow from the filter to make swimming around in general easier – Your guppy will be struggling to swim at the best of times and having a powerful jet of water from the filter return isn’t going to help.

  • Place the guppy in a breeder box – If your guppy is placed into a smaller volume of water, it may be able to move around and find food a little more easily.

  • Hand feed if necessary – If your guppy is unable to swim, you may need to hand feed it. This can be tricky, but with a little practice you may be able to get it to eat some flake food from your fingers.

I have to be honest, in my experience, a guppy rarely recovers from swim bladder issues. Often the kindest thing to do is humanely euthanize your guppy.

I have written a number of articles on the most humane way we can euthanize our fish when we need to. You may be interested to read this article titled How to Euthanize a Sick Guppy.

How To Prevent Swim Bladder Disorder In Guppies

As with so much in life, prevention is better than cure. There are a number of things we can all do to reduce the chances of our guppies getting swim bladder disorder.

Keeping the water clean is extremely important. Having a good filter is half the battle, but regular water changes are really the key. I try to change about 30% of the water in my guppy tanks every week. This helps keep their water ‘sweet’ and prevents nitrate levels from building up.

Feeding good quality foods will also help reduce the chances of a swim bladder disorder. Poor quality foods are bulked out with ‘fillers’. These fillers offer our guppy no nutritional value. In my opinion, feeding high-quality food like Bug Bites from Fluval (read my article on Bug Bites) is crucial for the long-term health of your guppies.

Regular feedings of live or frozen daphnia or brine shrimp help keep your guppies digestive systems in check. Both foods are a natural laxatives and help food pass through your guppy’s stomachs.


About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James
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