White Foam in Aquarium – Causes & Solutions
A widespread situation for all aquarists is the appearance of white foam on the aquarium water’s surface. Because it is such a common problem, its causes and treatment are very well known.
White foam in the aquarium. What is it?
The white foam on the aquarium water surface arises due to the accumulation of proteins and chemical compounds, mainly nitrogen, accessible in the water; these compounds originate in the decomposition of organic matter, such as leftovers, excreta, etc. The amount of protein may also be out of balance due to factors such as a dirty filter, some fish that died and was not removed, plants decomposing, among other factors.
Let’s understand more about these possibilities to trace the problem’s origins and the correct method to solve it.
What can cause this accumulation of proteins and compounds in water?
As mentioned above, this is likely due to degraded aquarium water quality, lack of periodic maintenance, and other factors.
Organic matter is being produced in excess, leading to a greater need for bacteria responsible for filtration. Familiar sources of debris that can pollute your aquarium are.
1.Excess food

The feed and other foods not consumed by the animals remain in the aquarium, decomposing and generating pollutant compounds that will degrade your water quality. Even if the fish consume all their food, it is essential to consider whether you are overfeeding them; the more the fish eats, the more waste it will produce.
2.Dead animals and plants
In large aquariums or many hiding places, ornaments, and plants, a fauna inhabitant can die in an area that prevents him from being noticed and removed. If the corpse is not removed or consumed in its entirety by the inhabitants, it will stay for a while, considerably increasing the level of pollution in your aquarium. The water degradation caused by dead animals left in the tank is the worst pollution generation scenario. Only one decaying fish can generate extreme ammonia and nitrite levels.
Like fish, plants also end up dying in the aquarium or simply losing leaves and flowers, which will be deposited on the bottom of the aquarium and decompose, creating problems if not removed.
3.Filters without maintenance

Aquarium water filters accumulate a lot of wastes, mainly related to mechanical filtration. All the water passes through it several times an hour, so any substance that is polluting the aquarium, sooner or later, will pass through the filter. The amount of debris deposited there can be enormous if you don’t maintain a proper routine of recurring maintenance.
How to deal with white foam
To deal with this problem, it is necessary to improve the cleaning and maintenance of the aquarium. Check regularly with the help of proper aquarium tests if your ammonia and nitrite levels are within the recommended range; if not correct, it is a sign that you are dealing with a debris problem in the aquarium. In an environment with correctly dimensioned filtration, the proper amount of food offered, the fauna population maintained at ideal levels, and tank maintenance up to date, it is unlikely that any white foam problem will occur.
Here is a list of how to deal with the primary sources of dirt mentioned above; if you follow these steps, your tank’s water quality will be stable at the ideal levels, which improves the inhabitants’ quality of life and eliminates the accumulation of foam on the surface.
1. Maintenance and Water Change
We should start with a partial water change to speed up the defoaming process. Remove some water from the aquarium and replace it with fresh, fresh, conditioned water. Never forget that it is necessary to treat any water coming from the supply network that enters the aquarium. Carry out weekly partial water changes, perform maintenance and cleaning of filters and glasses, and aspiration of the substrate with the siphon.
2. Fish feed
Feed your fish more often throughout the day but offer a small amount of food; this way, in addition to the fact that most fish have better use of the food provided, this technique avoids food leftovers. Always use feeds of excellent quality and specialized for your fauna.
3.Dead animals and plants in the aquarium
Remove it immediately whenever you notice that one of your aquarium’s inhabitants has died. Any animal decomposing can cause its ammonia and nitrite levels to explode. Likewise, if you haven’t seen one of the fish for a long time, look more closely at the corners and decorations of your aquarium. He may have died in some hard-to-reach place, which can cause you not to notice him, and he ends up becoming a hidden source of many problems.
Any planted tank ends up generating plant debris that has come loose and remains in the tank. Whether it’s leaves, flowers, or stems that have died or been pulled out in some way, it’s always essential to remove any debris buildup. Dead plants are not as harmful as decaying fish, but they are still a significant source of pollution.
Always check the condition of your filter; if it is filthy, clean it. Avoid going through periods or general maintenance without checking how the filters are, even if it doesn’t look dirty. A filter with a lot of debris will not only have an accumulation of dirt decomposing, but it can also become clogged, decreasing its filtering ability.
4.Foam in Betta’s aquarium
It is widespread to see in Betta and other male Gouramis aquariums the appearance of a specific foam on the surface of the water, but in reality, this is a nest of bubbles.
They are agglutinated air bubbles on the water’s surface, usually under a leaf or something like that; these bubbles form a nest. After mating, the male will deposit the fertilized eggs in the future.
So if you notice foam in the Betta’s water, take a good look at your fish. If he is creating bubbles on the water surface himself, it means he is setting up his bubble nest, and you have nothing to worry about; otherwise, test the water parameters and proceed with the correction.
A betta building a bubble nest shows that he sees the aquarium as his territory is so confident and healthy that he feels ready to breed, even though he doesn’t have any females around. If the foam is surfacing without being created by the Betta, it’s vital to assess what’s wrong and treat your tank using the information in the sections above.
Other common causes of white foam formation in aquariums
Although the most common cause of foam is pollution in aquarium water, this is not always the case. Other possibilities need to be investigated and dealt with if it is a problem. Here’s a list of other common causes of aquarium foam.
1. Turbulence in the water
The movement of the water itself can cause excess production of bubbles, causing the formation of foam in the water stream. If the amount is too large, these bubbles can accumulate on the surface. The possible cause of this excess of bubbles is the filter’s flow too strong, causing an exaggerated current. Over time, the bubbles eventually break up, but if you’re producing bubbles faster than they explode, you might end up with some accumulation on the surface of the water. In any case, this accumulation does not harm your aquarium at all; at the most, it can have an unpleasant aesthetic impact, but strong flow can come to hamper fish and stagnant water animals.
2. Bubble Nest
Some fish, as part of their mating ritual, produce bubble nests. These nests, formed by the male, attract the female to begin the mating process. Soon after mating, the eggs are fertilized and deposited in the bubble nest. If this is the case, the nest persists on the surface until the eggs hatch with the fingerlings. This is the case with species such as Bettas and Gouramis. So if you have one of these fish, and they are nesting, don’t worry. This is a sign that your aquarium is in excellent condition, as fish usually only reproduce in aquariums with perfect conditions and almost no pollution.
3.Medicines and other chemicals
Some chemicals and medications can leave a residue in the water. If you have used any type of chemical treatment, this could cause the accumulated foam. Therefore, after the end of the treatment, increase the quantity and frequency of your partial exchanges to eliminate all substances left by the medications.
4. Soap and detergents
Another prevalent and hazardous cause is the use of soap. Often the accumulated foam is due to small soap residues found in the aquarium. These can be due to their use in cleaning any element of the aquarium (ornaments, stones, etc.) or even from the hands of someone who placed them in the tank’s water. If even a drop of detergent gets inside, it can cause a large amount of foam. This is one of the most challenging cases, as soap is harmful and can even kill fish and shrimp. If you suspect this has occurred, perform a sizeable partial exchange (above 75%) and, on subsequent days, smaller exchanges (around 50%). Do this for a week to remove or significantly reduce the amount of soap dissolved in the water.
5. A prevalent problem
Whenever you find foam in your aquarium water, investigate the causes. Measure ammonia and nitrite levels. If the levels are within the correct range, consider whether this could be one of the alternative causes cited in this guide. After finding the cause, treat the problem accordingly.
Foam is a common problem many aquarists face and easy to solve, be patient and continue taking care of your aquarium with its periodic maintenance.