Why Do Guppies Blow Bubbles? (With Quick Solutions)

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Quite frequently, I notice odd behaviors in my fish tank that get me worried. For example, there was a time when I noticed that my guppies consistently blew bubbles at the top of the tank. To make sure my guppy isn’t sick, I began researching the reasons for that phenomenon pretty profoundly.

Guppies typically blow bubbles due to low oxygen concentration, secondary to overcrowded aquariums, and stuffed vegetation. To overcome the oxygen deficiencies, guppies breathe more rapidly, blowing bubbles as a consequence. That also happens when ammonia accumulates and burns the fish’s gills.

As we move forward in this article, I will show you what steps you should take to treat a guppy that frequently blows bubbles. I will also share a few tricks that will help you remove existing bubbles from your fish tank, so your aquarium will appear clean and tidy.

Also Read: Stress In Guppy Fish

Why Is My Guppy Making Bubbles?

Bubbles are nothing new in aquariums. Filters and air stones generate them all the time. You will also find them on plants, resulting from all the oxygen they have produced via photosynthesis. That is called pearling.[1]

The bubbles sit on the leaves, and, from certain angles, they look like jewels. On occasion, agitation in the tank is to blame for all the bubbles you see, especially when you add water to the aquarium.

You can also blame the presence of bubbles on a heater that was recently activated. Because cold water holds more oxygen than warm water, when you activate your heater to warm the water, it releases the oxygen as bubbles.

On the whole, bubbles are not a significant concern. They should only worry you if your guppy is the source. Some aquarium fish have a reputation for producing bubbles. Bettas are among the most common examples.[2]

They blow bubbles as a way of attracting mates. They also build bubble nests that are used to provide oxygen to their eggs and fry.[3] However, these attributes don’t apply to guppies. They are not known for blowing bubbles.

In many cases, guppies that blow bubbles will also frequent the upper sections of the tank. If you have noticed this behavior in your fish, the tank conditions are probably to blame:

1. Low Oxygen Concentration

Oxygen usually comes from the air surrounding the tank. It diffuses into the water through the surface. Yet, as was noted above, you can also rely on plants to produce oxygen via photosynthesis.[4] The process takes place during the daytime and reverses at night.

Guppies use their gills to draw oxygen from the water. If the oxygen levels in the tank are deficient, the guppy’s breathing will become labored. That is because its body works harder to meet its needs by extracting as much oxygen as possible despite the limited supply.

You shouldn’t be surprised if you see the guppy releasing bubbles at this time. It will either release the bubbles within the tank before rushing to the surface or rush to the surface and blow bubbles. Either way, the blowing of bubbles among guppies could be a sign of rapid breathing.

2. Inappropriate Water Quality

Oxygen levels in a tank can deteriorate for several reasons. One of those reasons is low water quality. If your fish is blowing bubbles, take a moment to determine the concentration of ammonia, nitrates, and nitrites in the tank.

You should also measure the pH and temperature. If you have many toxins, and if the pH and temperature are either too high or too low, your guppy could manifest its distress by blowing bubbles. It will also spend a lot more time on the surface.

Ultimately, your fish will tell you whether its behavior is expected. Bear in mind that some aquarists have fish that blow bubbles simply because they want to. It is a personality trait that doesn’t pose a threat to their well-being.

However, if the blowing of bubbles is a sign of trouble, you will observe additional symptoms. For instance, if the tank has an oxygen deficiency, the fish will become sluggish over time. If your fish is healthy and happy despite this odd aspect of its behavior, you should leave it alone.

Ideally, guppies should live in water with the parameters:

  • Temperature: 72-82 degrees F.
  • Water pH: 6.8-7.8
  • Water hardness (dGH): 8-12.

3. Stuffed Aquarium Plants

As was mentioned earlier, plants produce oxygen through photosynthesis.[5] That naturally happens when living plants are exposed to light. Hence, during the day, living plants in your tank are likely to produce bubbles.

Nevertheless, during the night, the process reverses, and the plants produce CO2 instead. If your aquarium features stuffed vegetation, your guppies might find it hard to breathe after sunsets. That will force them to breathe rapidly during the night.

Then, you will see bubbles covering your tank in the morning. The night hours could be dangerous for some fish due to the drops in oxygen being too dramatic. Yet, make sure not to confuse those with bubbles produced by the plants. Those mainly accumulated during the day.

4. Overcrowded Tanks

If your aquarium occupies too many fish, oxygen levels might drop even during the day. Since all fish rely on the same source of oxygen, they will compete over it until the levels become unbearably low.

Labored breathing in overcrowded tanks gets even more severe if the water is stagnant. Since there is no water movement, oxygen cannot dissolve into the water from the tank’s surroundings. That will cause rapid breathing in guppies and bubble accumulations.

The issue becomes even more severe in tanks with relatively large fish, like Oscars or large Catfish. Relatively large fish consume more oxygen than small ones. Also, tiny fish like guppies are more susceptible to oxygen deficiencies.

Also Read: Why Is My Guppy Shaking?

How to Treat Guppies That Frequently Blow Bubbles?

The bubbles your guppies blow are not a problem. They will dissipate soon after. They won’t accumulate in any fashion that might make them an eyesore. However, the fact that your guppies are blowing bubbles should concern you, mostly if you have observed additional symptoms such as loss of appetite and lethargy.

If you want to curb this behavior, you must attack the factors causing their distress. For instance, if you learn that their aquarium has an oxygen deficiency, you can improve aeration by using wands, air stones, and pumps.

For water quality checks, I highly recommend the API Aquarium Test Kit (link to Amazon). That affordable bundle allows you to measure the pH, ammonia, nitrates, and nitrites in your tank quickly and accurately.

Bear in mind that high ammonia levels could burn your guppy’s gills. Hence, if you find that the water quality has deteriorated, you should perform more frequent water changes. Start by replacing 10-15% of the water every two days.

If you keep using tap water to fill your aquarium, you should suspect chlorine toxication. The chemical is used to treat tap water and is quite poisonous to fish. That is why you are encouraged to de-chlorinate your aquarium water using products like the API TAP Water Conditioner (link to Amazon).

Yet, none of these steps will help your situation if your tank is overstocked. Guppies require tanks of at least 5 gallons. Forcing large numbers of guppies to live in small tanks will lead to overcrowding. 

That will produce oxygen deficiencies, not to mention a spike in toxins. Both of these factors will encourage the blowing of bubbles in guppies. That is why I recommend diluting your tank’s population, including relatively large tankmates and redundant plants.

How do I Get Rid of Bubbles in my Fish Tank?

Getting rid of bubbles in fish tanks involves these steps:

  1. Pour new water into the tank using a clean slate positioned at an angle.
  2. When necessary, add fresh water close to the tank’s surface.
  3. Position your filter tube’s outlet below the waterline.
  4. Warm new water before adding it to the tank to release dissolved oxygen.
  5. Clean your tank’s walls and plants using a clean cloth or your bare hands.

Those steps are relevant if the bubbles in your tank are due to inappropriate water introduction. However, you shouldn’t follow them if the bubbles come from your fish. Instead, you should follow the steps mentioned earlier.

However, if your fish appear healthy and the bubbles have nothing to do with them, the following tips may solve your situation: 

1. Lower Agitation

Bubbles will form in your tank whenever you agitate the water by filling it or topping it off. That can happen during a water change. Sometimes, this action produces so much agitation that it creates foam.[6]

You can prevent this situation by holding a clean plate at an angle over the aquarium while pouring water. That will prevent the water from splashing into the aquarium and reduce the agitation.

Another trick would be pouring the water close to the aquarium’s surface. That will prevent oxygen from dissolving into the poured water on its way to the tank. However, doing that too frequently could potentially harm your fish due to oxygen deficiencies.

If you have created bubbles in the tank, they will disappear in a few days, even without using the tactics above. Nevertheless, if they are attached to the decorations and glass, and their presence irks you, it isn’t that difficult to rub them off with your hands.

2. Position Your Filter Right

Filters will produce bubbles if their outlet is positioned above the water. That allows the stream of water they produce to trap air before it enters the tank. You can resolve this complication by positioning the outlet below the water surface.[7]

You could also point the outlet to one of the tank’s walls. That will allow the water to enter the tank without splashing the surroundings. If you choose that method, place the tube’s end as close as possible to the water surface.

3. Elevate temperature

Coldwater will release its reserves of oxygen in the form of bubbles when you turn on the heater. However, these bubbles are not a problem. They will disappear once the water reaches the required temperature.

If a water change is at fault, that is to say, you added cold water to the warm water in your aquarium, producing bubbles, the easiest solution is to warm the fresh water before you add it to your aquarium.

4. Wipe Existing Bubbles

Besides prevention, you can also take steps to eliminate the current bubbles in your tank. The easiest way to do that would be using a clean, soft cloth. You could also use your bare hands to remove trapped bubbles on your plants or the tank’s walls.

Either way, make sure that you’re not contaminating your water with soap detergents or chlorine. That could potentially attach to your guppies’ gills, forcing them to breathe even more rapidly. Instead, try maintaining a sterile environment.

Also Read: Guppy Tail Drooping


If you notice that bubbles accumulate in your fish tank, it doesn’t necessarily mean trouble. That could be because the water you’ve poured splashed around, dissolving oxygen in the process. However, guppies that blow bubbles should worry you.

That is because blowing bubbles is a sign of labored breathing in guppies. Start by testing your water for toxins like ammonia and nitrates. If those are within the desired range, try removing a few plants or diluting your aquarium’s population.

It would help if you also looked for additional worrying signs. For example, guppies that suffer from low oxygen will also appear sluggish and frequent the tank’s higher sections. If that is the case, you should act quickly before your guppy cannot handle it any further.


  1. https://www.petplace.com/article/fish/pet-care/small-pet-care/fish/bubbles-fish-tank-mean/
  2. https://en.wikipedia.org/wiki/Bubble_nest
  3. http://thetyedyediguana.com/blog/have-you-seen-your-betta-fish-blowing-bubbles-heres-what-its-really-doing/
  4. http://www.howfishbehave.ca/pdf/oxygen.pdf
  5. https://www.adana.co.jp/en/aj_backnumber/archives/824
  6. https://www.thesprucepets.com/foam-on-aquarium-water-1381213
  7. https://fishlab.com/bubbles-in-aquarium/