Is It Necessary For A Fish Tank To Have Bubbles?

One day I was at the fish store to buy some fish and I saw bubbles at the surface that I have never seen before and was wondering, what are these bubbles? And I decided to do some research.

Do a fish tank needs bubbles? It’s not necessary to have bubbles, not as long as you have well-oxygenated water. To oxygenate the water you don’t need bubbles but they could be a help to add oxygen.

The bubbles in a fish tank could appear for a lot of different reasons. In this article I will go through why do these bubbles appear, when do you want them and when don’t you want them.

Why Are The Bubbles Appearing?

The bubbles are gas, often oxygen, that rises to the surface of the tank. There are two different reasons for the bubbles to appear. Either you add them or they are appearing by themselves in the tank.

Why you would add bubbles to the fish tank have different reasons. It could be that the oxygen levels are too low in the tank. To know if the tank has enough oxygen in the water you look at the fish and see if they are going up to surface to breath air.

If your fish needs more oxygen in the water, then it would be a good help, but not a criterion to add bubbles.

If they are your fish tank could have too low levels of oxygen in the water. If this is the case, you might need to add bubbles in your fish tank.

You see, fish is also in need of oxygen just as we humans are. The fish is breathing the oxygen that is in the water itself. And just like humans, the fish will die if it’s not provided with sufficient levels of oxygen.

To raise the level of oxygen in the water you could put in an air stone that provides bubbles to the water.

The bubbles from the air stone are not giving oxygen to the water. The oxygen is captured in this bubble.

What makes the water more oxygenated is when the bubble pop at the surface. Then it brakes the surface tension and oxygen from the air around the tank is dissolved in the water via the surface.

Another way to add oxygen to the water if you don’t like the look of an air stone is to direct the flow from the air pump towards the surface.

The flow will break the surface tension and oxygenate the water.

There are natural causes of bubbles appearing.

The heater could make bubbles appear. It’s because the heated water having a harder time holding the oxygen than the cold water has.

When the water is heating up the oxygen has to go somewhere and is leaving the water as oxygen bubbles.

Plants will also make bubbles. In school, you have probably read about a process called photosynthesis.

That’s what makes the bubbles appear from your plants in the tank if the water is well oxygenated.

Don’t worry if the plants are not producing the bubbles though! I don’t necessarily mean that your plants are dead. The oxygen dissolves in the water before it has a chance to make the bubbles if the water is low in oxygen.

If your plants are dead or you have a lot of dead algae and see bubbles rise to the surface it’s a bad sign. These are the kinds of bubbles that you don’t need!

It’s ammonia produced from the nitrogen cycle and it could do harm to your fish. If that’s the case, probably multiple water changes are needed to get rid of the high levels of ammonia in the water.

If you see bubbles at the surface and you have fishes that in nature live in low oxygenated waters, like the labyrinth fishes as Betta and Gourami.

Chances are that they want to make some babies. The bubbles could be a bubble nest that these species are making to breed.

The eggs are put in the nest before they hatch. If that’s the case, let them have their fun and hopefully you will enjoy taking care of some fry.

When To Not Add Bubbles To Fish Tank

You don’t want bubbles if your tank is too oxygenated, then it could be damaging for the fish and plants.

As you remember from school, plants need carbon dioxide for the photosynthesis and if it’s too much oxygen in the water, it makes less space for the carbon dioxide to dissolve in water and the plants are not able to use the carbon dioxide.

If you then add more oxygen to the water it will get even harder for the carbon dioxide to dissolve and the plants will then grow much slower or even die if the oxygen levels in the water are that high.

For fish, too high oxygenation in the water could lead to gas bubble disease.

It makes small gas bubbles appear on the gills, eyes and other parts of the fish. It’s a deadly disease for the fish

A high oxygenated tank is not the most common cause of gas bubble disease but it’s a possible cause and that’s why it’s a bad idea to put more bubbles into an already highly oxygenated fish tank.

How Much Oxygen Is Needed In The Water?

There is no simple answer to the question since it depends on a lot of different things. Some of the factors are:

  • The temperature of the water
  • The amount of fish in the tank
  • The size of the fish in the tank
  • If the fishes are fast swimmers or not
  • The number of plants

In short, faster and bigger fishes are generally consuming more oxygen then smaller and slower fishes are.

If you are having a lot of fish they will also consume more oxygen and then the oxygen levels need to be higher in the water.

To see if there is enough oxygen in the water is impossible just by looking at the water. Instead, look at the fish and see how they behave.

If the fish’s gills are moving fast, the movement is slower and even if the fish is going up to the surface to get some air you have signs that the oxygen levels might be too low in the water.

If your fish are at the surface breathing you should do something the moment you discover it.

The first thing you need to do is water change, at least 50%. It will buy you some time while you figure out what’s causing the lack of oxygen.

To measure the oxygen there is some special kind of kits measuring the oxygen levels. It’s overkill for most fish keepers though. Oxygen levels are not that big of a problem for most.

Pros And Cons Of Bubbles In Fish Tank

As in everything, there are pros and cons. That’s also the case with the bubbles in the fish tank.


  • It oxygenates the water
  • It makes the water more lively and fun to look at
  • It looks good for some people
  • It could mean babies if you have fish doing bubble nest


  • Risk of gas bubble disease
  • Slow growing plants
  • Harder to swim for smaller fish when there are too many bubbles
  • Bubbles could stress the fishes

An air stone is a good complement to the fish tank to get some movement and additional oxygenation in the water.

Just be aware of the cons and you will be fine. There are other things that are more alerting and more important to keep an eye on in your fish tank!

Bubbles are for the most part not a concern for the average fish keeper. But it’s important to be aware and discover if something is unusual.

Related Questions

Is it necessary to have an air pump in the aquarium? It’s not necessary but it’s good to have since it helps oxygenate the water and also adds a current to the tank.

Why is the water cloudy and bubbly? It’s probably temporary. It could be a disruption the bacteria flora in the tank, it could be debris from the filter or gravel. The bubbles are probably oxygen escaping from the water.


I have been a fish keeper a big part of my life. During the years I have gathered and searched a lot of information about fish keeping and here, on the website, is where I share that information to help you with your fish keeping. I want to provide the information that I didn't get when I had a question about my fish tank.

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