White foamy bubbles covering fish tank – What to do?

If you find bubbles on top of fish tank water, don’t panic – it could be a number of things. Even though these bubbles or foam will not harm your pet fish, you should still be aware of what causes bubbles on top of a fish tank and how to get rid of them.

Sometimes fish tank bubbles are normal, or it could be due to one of five aquarium issues. It could simply be a bubble nest, soap residue, bubbles formed by oxygen in the water, agitation from the filtering system, or protein accumulation.

Here we will explain each of these aquarium challenges and how to remedy the situation.

What Is Bubble Nest Foam in an Aquarium?

Some male fish create a sticky, foamy bubble nest to attract the female for mating. When your male fish are building bubble nests, it is an indication that they are healthy and content. The hope is for a female to swim into the area to begin the mating process. So, it is best to leave these bubbles undisrupted, or else you may stress out the male foam builder.

These clusters of bubbles on the surface of your fish tank are part of the breeding process of betta fish or “labyrinth fish.”

Betta fishes, aka Siamese Fighting Fish, are very territorial. In addition to the bubble nest being an attraction to the female Betta, it serves as a hatchery to safely secure eggs within the bubbles keeping them moist and oxygenated. Bubble nests are important because betta fish’s natural habitat and breeding grounds are often a shallow, dirty water pond that does not have much oxygen.

The male betta fish’s job is to protect the eggs after the female Betta has released them. They will guard the bubble nest with ferocity and even search out, find, and replace any eggs that have fallen from the nest.

Bubbles in the Fish Tank After Water Change

After changing the water in your home aquarium, you may notice bubbles on top of the fish tank or the walls of the fish tank. When you see fine micro bubbles covering the glass and other tank surfaces, it is likely due to the rapid change in water temperature. Cold water holds a lot more oxygen than hot water, so when you add cold water to your tank, the rapid temperature change can cause oxygen to vacate the water in the form of air bubbles.

These bubbles should disappear within a few days, but if they bother you, simply wipe them away.

These same types of bubbles may appear on your aquatic plants as they produce oxygen through the process of photosynthesis. What happens here is the aquarium plants will feature pearl-like bubbles on the leaves and stems as photosynthesis converts CO2 and other nutrients into oxygen bubbles. These bubbles are completely harmless and show that your plants are healthy and growing well.

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Water Agitation From the Filtering System

Air bubbles on top of fish tank water can easily form when water is agitated. And this can happen when you top off or when you’re filling the aquarium tank. The agitation of the water pouring into the aquarium is enough to cause the water to foam or bubbles to appear, which is normal and even happens at any source of water agitation.

The solution here is to add water more slowly or allow the water to slide down an angled plate into the tank instead of forcefully splashing. These air bubbles will not harm your fish, and they should dissipate rather quickly.

If the water is foamy and you have a spray bar, it may be that the spray bar is generating enough pressure that the water foams, a common occurrence in saltwater aquariums. Try adjusting the flow of your filter or spray bar to produce less water agitation. But make sure your type of fish prefers a slower water current because some may not thrive in a tank with too little or too much water flow.

Protein Accumulation Can Cause Bubbles

Another cause of white foamy bubbles covering your fish tank could be the result of protein-based waste. When fish leave excrement, some of the waste can coat small air bubbles, causing these bubbles that would normally dissipate to stick together in a foul-smelling foam. While it can happen in freshwater tanks, it is more common in saltwater aquarium systems.

If protein foam is the cause of bubbles on top of the fish tank, then it’s time to give your aquarium a good cleaning. Also, inspect the filter to ensure it is clean and remove any floating or gravel debris from the water. Protein accumulation that causes white foam or bubbles is easily eliminated with protein skimmers that work to remove excess protein from the water’s surface in saltwater tanks.

If a fish has died and decomposed without you noticing, this will be another rich protein source. Always keep a count of your fish daily to make sure none are missing. A decaying plant or a hidden, dead fish are usually the sources of the white foamy bubbles that are protein-based waste. Change the aquarium water regularly and maintain your aquarium filters to eliminate protein foam in your tank.

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Leftover Soap Residue

If you have recently cleaned your fish tank, leftover soap residue can form bubbles, especially when the water is agitated. Don’t use the tools for cleaning your fish tank for other cleaning purposes. This is especially true of the scrubbing pads and water buckets you use. Even a small amount of cleanser can cause rainbow-tinted bubbles to form within the tank.

If your aquarium becomes tainted with soap, it will need to be drained, rinsed, and re-filled with clean, dechlorinated water. Make sure the water approaches the same temperature as the previous water before returning your fish. If soap is the culprit, even your filter and filter pads may have to be switched out or thoroughly cleaned.

How to Get Rid of Bubbles in a Fish Tank

  • If protein foam is the culprit, then give the aquarium a good cleaning. Replace or clean the filter and remove any dead plants, leaves, fish, or other debris in the aquarium using a gravel vacuum.
  • If it is a bubble nest, leave these bubbles undisrupted, or else you may stress out the male bubble foam builder.
  • When bubbles are due to oxygen-rich water, they should disappear within a few days, or you can simply wipe them away.
  • When bubbles occur during a water change, add the water more slowly or allow the water to slide down an angled plate into the tank.
  • If the white foam is due to soap in the aquarium water, then the aquarium must be emptied, cleaned, and rinsed with fresh water added.

Finally, air bubbles generated by your filter can eventually build up to where bubbles are floating on the water’s surface or any other place where they can stick. Inspect where the water filter discharges water back to the aquarium because this may cause air trapped with the water, forming bubbles that float around your tank. You may need to more water to your aquarium until the water level is in line with your filter outlet.

If you have a high force of bubbles entering the tank, the impact on small fish can be deadly. And, if you’ve added an air stone to increase the amount of dissolved oxygen in the water, depending on the type and size of your fish, the air bubbles generated by an air stone can distress some fish.

7 Reasons Why Your Fish Tank Has Bubbles

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Nadine Oraby

My name is Nadine; I am a passionate writer and a pet lover. People usually call me by the nickname “Joy” because they think that I am a positive and joyful person who is a child at heart. My love for animals triggered me to create this blog. Articles are written by vets, pet experts, and me. Thanks for visiting. Your friend, Nadine!

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