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Bubbles (or foam) in your fish tank are a cause for concern, especially for new aquarists with not much experience keeping fish.
Fortunately, most bubbles causes in a fish tank are not unsafe for fish, more so in the short term. The only kind that should warrant a closer look are persistent forming bubbles caused by an excess protein film layer or ammonia.
If all you have are just bubbles from your air-driven filter or air stones that pop in a few minutes or bubbles nests made by anabantids (Bettas, Gouramis), then your fish are safe.
You may also get bubbles around your aquarium whenever you do a water change, which are also not harmful and clear out in due time.
In my fish-keeping experience, these are the six scenarios where I’ve noted air bubbles forming in my fish tanks.
- Air-driven filters, bubblers, and wave makers
- Water change
- Bubble nests
- Dirt (protein) films on the water surface
- Excess toxic chemical like ammonia, chlorine
- Fish medication
Now, let’s explore the causes of bubbles in tropical fish tanks for more clarity.
What Causes Air Bubbles in Fish Tanks
As I mentioned above, if you do not have anabantids and you are sure the bubbles in the fish tank are not from your filter or airstones, then your water is dirty, or you have oils (or soap) in your tank.
Bubbles from Protein, Soap Dirt in Your Fish Tank
Now, if the bubbles in your fish tank are foamy and have an odor, then they are most likely a result of protein foam, which appears when protein-based waste coats tiny air bubbles in your tank and keeps them from popping.
Mostly, these bubbles will form together at the surface of the water and are an indication your fish tank needs some cleaning.
Protein foam is more common in saltwater setups, but it sometimes appears in freshwater aquariums.
The best remedy for protein foam in saltwater tanks are proteins skimmers, a unique type of filter for oily dirt.
Please note protein skimmers are not as effective in a freshwater fish tank.
That said, bubbles resulting from soap or oils in your fish tank will foam almost in the same way protein dirt bubble do, and you can easily get confused.
As such, anytime I notice foaming in my fish tank, I consider the worst and take the necessary measures as soon as possible. A good cleaning and up to 20 percent water change often does the trick.
Bubble Nest Foam
In the aquarium hobby, we have some common labyrinth fish such as bettas and gouramis that breathe at the water surface, plus most also make bubble nests to attract mates.
Either of these reasons may be why there are bubbles in your fish tank.
Fish that make bubble nests, such as betta, live in shallow, muddy puddles with stagnant or slow-moving water that is dirty and has low oxygen.
Because these waters are poor breeding ground, unable to support eggs and fry, I believe bubble nests are the finnies only way to reproduce given the conditions.
Think of the bubble nest as a sort of cocoon that allows the eggs and newly hatched fry a safe spot, the same way a cocoon protects a caterpillar.
Bubble nests are usually located beneath debris or plants in the finnies' natural environment. But in the fish tank, my betta seems to prefer making it in a corner spot near the surface.
Now, another thing I mentioned is fish with the ability to breathe at the surface of the tank (and may form bubbles). Interestingly, betta and gouramis make part of this small group of finnies.
They possess unique organs called the labyrinth that help them breathe surface air, something other finnies can’t do. I believe this has something to do with adapting to their natural environment as well.
Due to the shallow, muddy water that’s barely moving, there is limited aeration meaning the fish needs to come to the surface for air.
If your fish tank has excess toxic chemicals such as chlorine and ammonia, the fish get their oxygen by floating to the surface and blowing bubbles.
However, if the finnies in your tank are not labyrinthed, they will gasp for air at the surface where the water is well aerated since they can’t breathe surface air like bettas or gouramis.
Bubbles in Your Fish Tank After Water Change
Bubbles in your fish tank usually form due to agitation in your tank when you fill it with water. The bubbles result from tiny air pockets inside the water that may get attached to the glass or float at the surface.
These kinds of bubbles are not harmful to your finnies and will pop in a short while. If they don’t disappear, then your water must have dirt elements causing the bubbles.
Plus, once they pop, they are nice and will aerate your fish tank.
Should You Leave Bubbles in Your Fish Tank
For the most part, bubbles are not bad in a fish tank and will not harm or kill your fish unless they result from dirt, including protein films.
Besides, even in the case of dirt in your fish tank, the bubbles are not expressly harmful to your fish. The dirt causing the bubbles is more likely what will cause your fish harm.
If betta and gouramis are building nests out of foam, let them be. The bubbles won’t harm the rest of your flock, but be ready for your new pretty fishies babies.
Power filters, bubblers, and air pumps system bubbles are ok as well. They will aerate your fish tank.
How To Get Rid of Bubbles in Your Fish Tank
There are several ways to get rid of unwanted bubbles in your fish tank. The most straightforward way would be to switch from an air-powered filter to an electrical unit since most bubbles result from these devices.
An electrical filter will run quietly and without putting bubbles in your fish tank.
If you have bubblers or wavemakers in your fish tank, it helps to switch them off when you don’t want bubbles in your aquarium.
However, please note that these solutions will only work if you have enough oxygen in your water.
Some bubbles will come from water that becomes soiled by fish waste, leftover food, fish medication, and even cleaners forming an oily dirt scum on your water.
To solve this problem in your freshwater aquarium, you will need to do a water change or replace your filter cartridge. You can also use a protein skimmer (specialized filter for oily-protein films), although they work better in saltwater aquariums.
You can use protein skimmers in your freshwater aquarium, but the physical mechanisms that make them effective in saltwater don’t work so well in freshwater.
Essentially, protein skimmers target oil films causing bubbles in your fish tank, the same way other filters aim at specific contaminants. The inner working may not be the same, but the results are akin to other aquarium filters.
Lastly, bubbles formed by anabantids like betta and gouramis are barely a problem, so there is no need to remove them unless you absolutely don’t want your finnies to breed.
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That’s all for this post, see you in the next one.
Have fun with your finnies🐠🐟.