Small bubbles all over the tank – Why? What to do?

Bubbles floating in the fish tank always amuse me. Fish swimming between those big bubbles gives a natural aura to the aquarium. But when I bought my fish tank, what I observed were small bubbles that weren’t going away. Those tiny water bubbles fretted me as I wondered if my water buddies were happy in there or not. I dug in the matter and got satisfactory answers after some research. These tiny bubbles can be bothersome, and if they are harmful, then you should know what to do to remove them.

So, here’s the kicker:

Small bubbles in the fish tanks are not bothersome to fish, mostly. But in other cases, when tiny bubbles make a foam and sit on the top of the tank, the fish might die if you don’t take any step. You have to clean all the toxins such as protein, ammonia, and chlorine from the tank to clear the bubbles. Your fish will thank you as they will be able to breathe easily.

Let’s see why these micro-bubbles appear in the tank and are they dangerous to your pet fish or not.

Why Small bubbles appear in the tank?

Why small bubbles appear in the fish tank?

When you have set your dream aquarium but then you find small bubbles floating all over then don’t panic.

Bubbles are common in an aquarium and some bubbles are a sign of a healthy habitat. Whereas, there are certain micro-bubbles that are caused by toxins and you have to get rid of them as soon as possible.

Small bubbles can appear due to:


At the very beginning, when you are filling water in your tank, you might see tiny bubbles forming a foam. These bubbles can turn the water slightly milky.

These bubbles are very common and not dangerous at all. They are caused by mere agitation when you fill the water too quickly. These bubbles go away on their own.

To avoid these kinds of bubbles, simply put a plate at an angle that makes the water flow smoothly in the middle of the tank. This smooth flow will prevent water from striking the wall of the aquarium, and, thus minimum bubbles will form.


The aquarium plants undergo photosynthesis just like other plants. But plants in the water release oxygen in the water and this form small bubbles. These oxygen bubbles even stick on the plants and some of them float in the water.

These bubbles are filled with oxygen so they are considered good for your fish. These bubbles show that your tank has some healthy plants that are releasing oxygen as a by-product during photosynthesis.

Bubble nest formation

Some male fishes, like Betta fish, produce small bubbles that accumulate in the tank for some time.

These are called bubble nests that are pretty common and not fatal for the fish. Labyrinth fish produce these bubble nests to attract females for mating purposes.

These bubble nests indicate that your fish are healthy. Even if there are no female fish in the tank, Labyrinths continue to produce bubble nests.


Soap and any kind of detergent are fatal for your fish. A small amount of soap is enough to kill your fish. So, when you see frothy, tiny bubbles that have a soapy texture then immediately change the water and clean the tank.

These frothy bubbles are not at all good for your fish so don’t use aquarium buckets for other purposes that require soap or other detergents.

Protein accumulation

Sometimes small bubbles appear that don’t go away. These bubbles might have a layer of protein on their surface that keeps them from popping.

Water contaminated with protein can kill your fish. Protein can accumulate from debris, dead fish, and dead plants. So, count your fish regularly and remove dead fish and plants immediately.

If you find small bubbles that make the foam and aren’t going away then clean your tank and fill clean, dechlorinated water.

Chlorine and other toxins

Small bubbles can also form due to chlorine, ammonia and other toxins that may accumulate in the tank. These bubbles are definitely dangerous and you should remove them immediately.

Tap water is usually chlorinated so don’t ever use tap water directly. You should dechlorinate water first before filing the tank. Also, change the water regularly to remove waste material.

Bubbling by fish

This may seem cute but it’s very critical when bubbles are formed because of fish breathing at the surface of the water. Fish deprived of oxygen inside the tank gasp and inhale oxygen from the surface. The gasping causes the formation of small bubbles.

Bubbling caused by fish gasping indicates that the water in the tank is unclean and doesn’t have enough oxygen.

You have to change the water and clean the filters so that water absorbs enough oxygen from the atmosphere.

Why your fish tank seem cloudy? Find more reasons here!

What to do to avoid small bubbles in the tank

As long as bubbles are produced due to agitation, pearling, and formation of the bubble nest, you don’t have to worry. These bubbles are normal and even healthy. The tiny bubbles formed doesn’t bother your fish and pop on their own.

But when bubbles are produced in the form of foam due to toxins, protein, and bubbling then you have to take notice. You should follow these steps to avoid these unwanted micro-bubbles:

  • Change the water every week. Keep a check on the level of ammonia and other toxins. If you notice frothing then change water immediately.
  • Use air pumps and stones to produce agitation so that water absorbs oxygen from the air and release carbon dioxide out.
  • Clean the tank filters on a regular basis. Unclean filters don’t clean the water and this results in the accumulation of toxins.
  • Don’t use tap water for your tank directly. Use de-chlorinators that are easy to use and not very expensive.
  • Trim dead leaves and stems of aquarium plants regularly. Dead leaves produce a protein that surrounds the bubbles in the tank.
  • Count your fish and remove dead fish whenever you find one. It’s fatal to leave the corpse inside the tank as it decomposes and produces toxins. Bubbles produced due to these toxins is definitely dangerous for your fish.
  • If your fish are gasping then change water as soon as possible. The bubbles produced by gasping indicate that the water inside the tank doesn’t have enough dissolved oxygen.
Ways to get rid of unwanted microbubbles

How to Differentiate between good and bad micro-bubbles?

You have to see for several signs to differentiate between small bubbles that are harmful and those that aren’t.

If you notice foam that doesn’t lighten with time then that means it has toxins in it. This is the time to change the water and take the necessary steps to remove the foam.

If the bubbles seem sticky then they’re harmful. These sticky bubbles will remain attached to the walls of the tank, plants, and at the surface of the water.

If you observe bubbles that float in the tank and pop on their own then they aren’t the harmful ones. These bubbles are quite normal.

If you aren’t sure whether these small bubbles are problematic for your fish or not then it’s better to change the water and clean the debris to be on the safe side.

The Takeaway

Small bubbles or micro-bubbles are produced in the tank due to many reasons. If they are produced due to agitation, pearling by plants, and nesting by Labyrinth makes then they are quite normal. You don’t need to worry as these bubbles aren’t harmful to your fish.

But if you notice soapy froth, small bubbles that don’t go away, and bubbles caused by fish gasping then these bubbles should be removed as soon as possible. These bubbles make water deprived of oxygen and the level of toxins rises.

You should keep your aquarium buckets aside just for aquarium use. Also, change water frequently, clean the filters and air pumps. Last but not the least, dechlorinate the tap water and make sure it doesn’t have any chlorine or chloramine in it.


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