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Are bubbles in a fish tank a problem? They just might be

Bubbles in fish tank? Here are 5 reasons they might be there (and what to do about it)

You’re always going to see some bubbles in an aquarium. Most likely, it’ll produce a steady stream from the filter, and that really just means that it’s working. But the filter’s also not the only source, and some bubbles may indicate underlying problems with your water or with your inhabitants. So, why are there bubbles in your fish tank, and how do you know if those little oxygen sacks indicate an issue or a healthy ecosystem? Here’s how to tell where they’re coming from and what to do about it.

Fish tank with healthy bubbles coming out of filter

Why there are bubbles on plants

As mentioned, your bubbles are often totally normal as part of a healthy tank that continues to cycle through water. This will especially hold true if you have live plants, which produce oxygen naturally and sometimes hold on to it in the form of bubbles. Of course, those eventually dissipate, at which point the gas inside seeps into the water. That’s good! Fish need to breathe just like the rest of us and do so through their gills by pulling oxygen from water in the tank. 

Boy watches his fish tank closely

Why bubbles are covering the surface

So, what happens when there’s not enough oxygen for your fish to function happily? If you see bubbles in a fish tank floating at the top and multiple swimmers coming up to them, that often means your tank lacks enough of the vital gas. When they can’t get it from the water, they’ll make their way to the surface and breathe the air. Some fish do this frequently, as do aquatic frogs and other nonfish aquarium dwellers, so don’t take that act alone as an immediate cause for concern. But a buildup of bubbles from too many fish breaths could tell you that it’s time to reexamine your levels. A water change or filter will fix the problem — make sure to slowly pour the water in for maximum effect. And look into any larger issues — your tank might be dirty or overcrowded. 

Bubbler in water of a fish tank

Why bubbles are clinging to fish

Finding them clinging to your fish should start to ring some alarms. Examine the bubbles closely and call an expert to determine the issue. Unfortunately, it could be ich or gas bubble disease, both big problems. If you determine that ich or another parasite is causing them, look to a few simple conditioners for a cure. However, gas bubble disease occurs when you make too many changes to the aquarium in temperature or pressure. Keeping your tank clean but without replacing all the water prevents this. Once your fish has it, submerge him in very deep, high-pressure water and call your fish doctor for assistance.  

Man cleans fish tank with a sponge

Bubbles that won’t pop

Sometimes this looks more like foam than individual bubbles, but it always means trouble. More specifically, you need to clean your tank and figure out why it’s getting too dirty in the first place. Check your filtration system and determine whether it needs replacing or an upgrade. Go through the deep-cleaning process, including gravel and accessories, and do a partial water change. Remember not to do a full water change except in extreme emergencies as that will introduce more challenges than it solves. 

Red betta making a bubble nest

Bubbles in a betta tank

Counterintuitively, your betta bubbles just tell you he’s good. It’s actually a part of their breeding process — if you did have a lady betta around, she would lay her eggs inside the bubble nest. This keeps them safe and secure in an oxygen-rich environment once they hatch. In her absence, he’s staying prepared, always ready to find a mate. You may even catch your betta in the act of gulping air and spitting it out so you’ll know their exact origin. We recommend letting him blow to his heart’s content.

While there’s no one cause of bubbles, they aren’t usually a concern. Look closely at where and how they are forming as well as if they have any particularly interesting characteristics. The best defense in your aquarium is a good offense: A proper filter, regular partial water changes, and a big tank will keep your problems to a minimum. If you can’t quite tell where your bubbles are coming from, go through a light clean, and full water test to spot any obvious problems. That usually does the trick.

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