Guppy Swimming Vertically: Causes And Preventions

Guppies (Poecilia Reticulata) are very popular in freshwater aquariums. They are peaceful species that come from South America.

Guppies are available in about 300 varieties, varying in sizes, colors, and tail shapes. They should be the most active inhabitants of aquariums, constantly swimming around in a playful mood.

If you find a guppy swimming vertically or upside down, don’t consider it an innocent behavior. Instead, you should stop to look closer.

The article will provide you with useful information on this topic.

Let’s scroll down to read more information!

Guppy Swimming Vertically: Common Causes 

The cause of guppy swimming vertically

Inappropriate Food

If your guppy eats stale or rotten food, it will most likely generate a lot of gas in the gut, entering its swim bladder and making your fish excessively buoyant. 

The same situation can happen to your fish if it gulps air when hunting for food from the surface. It can also be the consequence of overfeeding or constipation.

In this case, you should stop feeding your fish for about three days. Then once this period ends, feed it peas (skinned and cooked).

Genetic Deformities 

Genetics can also cause the guppy’s swimming habits. Some species are born with genetic anomalies, and their swim bladders might be deformed from birth. Such cases are often the result of routine inbreeding.

There is no way to help fish with naturally deformed swim bladders. You can’t resolve this problem any other way. It is impossible to rewrite the DNA of your guppies to eliminate this ailment.


Physical confrontations between guppies or guppies with tankmates can expose their swim bladders to injuries. The consequences should depend on the extent of the damage. Some wounds never heal.

If physical injuries cause guppy swimming vertically, just isolate it. Put it in another tank to recover. 

Unsuitable Temperatures

Water temperatures lower than ideal can harm your guppy’s body. It will slow down the digestive process and enlarge the gastrointestinal tract. It can also exert pressure on your fish’s swim bladder and deform it.

If an enlarged intestinal tract or stomach leads to swimming disorders, we recommend raising the temperature (from 78°F to 80°F). This range is quite narrow, so you should use the aquarium heater to get the job done.

Increasing temperature is encouraging for various causes of swim bladder diseases. It is also okay to add some aquarium salt.

But sometimes, the swim bladder damage in guppies is too severe to treat. So you shouldn’t expect positive results in all cases.

Environmental Changes

If exposed to sudden environmental changes, guppies can suffer from shock, temporarily affecting their swimming.

Potential causes might include a sudden drop or spike in water temperature.

This situation usually occurs when you introduce new fish to your aquarium.

If your guppies swim erratically due to abrupt changes in their environment, you can treat the shock by removing the elements that have created stress.

Bacterial and Parasitic Infections

Parasitic worms are typically not a concern as they are commonplace in fish.

They are even innocuous in the ideal condition. But a large mass of worms in the fish’s stomach can form a kind of instability, complicating its swimming behavior.

In addition, bacterial infections can be severe, compromising the functions of your fish’s swim bladder, which debilitates its ability to swim properly.

Bacterial infection can affect the way your guppy floats, but such symptoms typically manifest when your fish becomes seriously sick.

In this case, it is best to seek medical help.  It is okay to get rid of parasites with antihelminthic medication.

On the flip side, you can treat bacterial infections with antibiotics. But we always recommend consulting a veterinarian to get the proper medical solutions.

Guppy Swimming Vertically: Preventions 

Introduce the Proper Tankmates

You can reduce stress in your guppy by removing aggressive tankmates. 

Prioritize non-aggressive individuals that can live in harmony with your guppies after introducing them to the aquarium.

If you cannot remove aggressive fish or replace them with peaceful ones, adding decorative items and plants to your tank is alright to give guppies hiding places.


It is unnecessary to kill guppies with genetic defects. Instead, moving them to a separate tank will solve the problem.

The purpose is to prevent these individuals from crossing with healthy ones to produce offspring with the same deformities.

Maintain the Tank

It is best to maintain a clean tank, which is free of toxins. We recommend installing a filter and removing dead organisms and leftovers.

Also, you should regularly test for elements like ammonia, nitrites, and nitrates

Always keep their concentrations at the recommended level. The simplest way is to change the water more often.

Also, you need to provide the proper water parameters for your guppies:

  • Temperature: From 72 to 82°F (From 22 to 28°C).
  • pH: From 6.8 to 7.8.
  • Hardness: From 8 to 12.

Feed Guppies Properly

Avoid overfeeding your guppy fish.

Avoid overfeeding your guppies. Instead, give them food in quantities so that they can consume it within up to three minutes. 

You also need to pay attention to the quality of the food. Always avoid stale food, which is bad for your fish’s digestion.


Why Is My Guppy Straight up and Down?

The main reason they do this is stress. It could mean they are not happy in the current environment for the following reasons:

  • Poor water conditions.
  • Overstocking and overfeeding.
  • Incompatible tank mates.
  • Improper tank size.
  • And more.

Is Swim Bladder Disease Fatal?

Yes. It can result in severe stress and untimely death.

Is Swim Bladder Contagious?

A swim bladder isn’t contagious from fish to fish.

How Do Guppies Normally Swim?

Guppies tend to be top swimmers, meaning they spend most of their time swimming near the top of your tank.

What Do Stressed Guppies Look Like?

Stressed guppies will lose some of their colors and become pale.


There are many causes of guppy swimming vertically, and fortunately, there is always a way to solve the problem (except for genetic deformities).

Hopefully, through the valuable information above, you can help keep your beautiful guppies healthy for a long time. If you have any questions about these fish, leave a comment or check out our other posts. 

Thank you for taking the time to read the post!