Swim Bladder Disorder in Freshwater Aquarium Fish

Aquarium fish can be exotic and beautiful to look at, but you have to remember that they are work and responsibility, just like any other pet. Many things can go wrong with your fish; some can be explained, and some can not. It is an essential responsibility to know all there is to know about being an aquarist before you do it. 

Many different diseases can affect your aquarium fish; fin rot, mouth fungus, iridovirus, white spots, and anchor worms. However, that is just a handful of issues. Some are viral, while others are bacterial or caused by parasites.

If you catch the disease early enough, some treatments can save your fish. However, there are a couple of rare exceptions where there are no treatment options. Ensure that you know all you can about the species you want and what can go wrong before you purchase your fish.

Swim bladder disease could be bacterial or caused by digestive issues. It can affect any species of aquarium fish but especially Balloon Mollies. The fish’s swim bladder is an internal gas-filled organ that aids in a fish’s ability to control its buoyancy. This allows them to stay at the current water depth without having to swim constantly.  

According to Wikipedia, Swim Bladder Disease is common in aquarium fish.

Today I am going to highlight Swim Bladder Disorder. We will cover what it is, the symptoms to look for, causes of the disorder, treatment, and how you can prevent it from occurring. I am also going to give you secondary options that may or may not help your fish. By the time we are finished today, you will be fully prepared to deal with swim bladder disorder.

What Is Swim Bladder Disorder?

Swim bladder disorder happens when the swim bladder of the fish is too full.

Remember, the swim bladder is an internal gas-filled organ that aids in the fish’s buoyancy ability. When it is too full, your fish may float at the top of the tank, swim sideways, sink to the bottom or float belly-up. 

The belly will look bloated, and the spine may even look curved. Swim bladder disorder is most common in goldfish, betta fish, and balloon mollies; but can occur in any freshwater aquarium fish species.

Most people do not know about this condition and assume their fish are dead when they see them floating upside down or lying on the aquarium’s bottom. 

Symptoms Of Swim Bladder Disorder

As mentioned above, swim bladder disorder causes fish to float, sink, swim sideways, and have bloated bellies. If you are unfamiliar with your freshwater fish’s natural behavior, it may be hard to figure out what is wrong. There are a wide variety of videos to watch so that you can compare the symptoms and behavior.

Typically the 2 most prominent symptoms are; distended belly and their swimming position.

The swimming position will be something similar to your fish swimming horizontally with their tail higher in the water than their head. Some species naturally swim this way, so you need to check your breed. If they are not designed for swimming horizontally, then chances are, they could have swim bladder disorder. 

Some fish with swim bladder disorder may not lose their appetite and will continue to eat normally, where other fish will cease eating altogether. So when you feed them, make sure you are paying attention to your fish. You can not just toss in food and walk away. 

Causes Of Swim Bladder Disorder

With swim bladder disorder, there are a variety of causes. Below are some of the known triggers.

Compression from other organsThe compression interferes with the bladder’s function. This is what interrupts their buoyancy. Sometimes, the organs’ compression doesn’t directly affect the bladder, but the organs around it; enlarged stomach, enlarged liver, kidney enlargement, impacted eggs, or a compressed intestine.
InfectionBacteria or other parasites can cause this. Bacteria and parasites occur because something is going on in your aquarium. Check all of your levels, such as pH, regularly.

Make sure you are doing the recommended water changes and other maintenance on your tank. Double-check your filter system when you do your water changes. When you set-up your tank, do your best to get high-quality equipment. 
Physical injuryAny type of hard impact on your fish can cause swim bladder issues. There are numerous ways physical harm can occur, so be sure you are extremely careful when taking fish out of the tank and not putting species together that will likely fight.

They can also run into tank decorations if the aquarium is too crowded, and this can cause injury to their swim bladder.

An easy way to explain compression; swim bladder disorder is caused by compression of the swim bladder, which could involve a distended stomach from eating too fast, overeating, constipation, or gulping air.

Eating fish flakes or freeze-dried foods that absorb water and expands will also lead to the intestine or the stomach becoming enlarged.

Treatment Of Swim Bladder Disorder

Your treatment options are going to vary, depending on why and how your fish contracted swim bladder disorder. Now would be a great time for your fish to be able to talk to you, tell you what ails him. Unfortunately, you cannot do a lot of it from a physical injury or a congenital disability. But you can definitely try any of the below treatment options. 

  • Feeding: the first possibility is the diet. Especially if you are feeding your fish too much, as stated earlier, this can cause organ compression. To rule out the diet, refrain from feeding your fish for 3 days. When you do begin to feed them again, feed them sparingly. Whatever they do not consume in 2 minutes needs to be removed immediately. If they do not seem any better after the 3 days of fasting, try another treatment option. 
  • Water temperature: while you are proceeding with the treatment options, you want to make sure that your tank water is 80 degrees. Cooler water temperatures can actually lead to digestive issues, causing bloating and buoyancy issues. 
  • Water quality: if your water quality isn’t up to par, then your tank could be infected. As mentioned above, you need to remember that routine maintenance and 25% water changes regularly are essential for your fish’s health. You need to check and clean (or replace) your filter during the maintenance of your tank. This will help in keeping infections at bay. You may need to move your fish to a different tank so that you can do a complete water change and thorough cleaning. 

You can also try feeding your fish a frozen pea after their 3 days with no food. Make sure the pea is completely thawed out. You can microwave or boil it for a few seconds and make sure to remove the skin.

Preventing Swim Bladder Disorder

The things that you can do to prevent swim bladder disorder are everything we have discussed above that could be the cause.

  1. Regularly, check pH (and other levels) frequently, and do 25% water changes at least once a month.
  1. Keep your temperature at least 2 degrees higher than recommended. This will help with digestion, aid in the avoidance of constipation, and help with buoyancy.
  1. Feed your fish only high-quality recommended foods. Only feed them what they can consume in 2 minutes and clear out the rest immediately. You always want to thaw frozen food out completely, soak dried foods for 2-3 minutes, and if your fish gulp air when they are eating, then try switching to a food that sinks to the bottom of the tank.

On top of these preventative measures, you need to pay attention to your fish. They are not something you just put in a tank, throw food at, and ignore. Observe them each time you feed them.

Are they active, swimming as normal, do they get excited at feeding time, and do they look healthy? If you see or sense anything different in your fish’s behavior, activity, or appetite, call your vet.

Additional Information

If it is determined that your fish has an infection, you will need to visit your vet for an antibiotic.

You can try adding a small amount of aquarium salt to your freshwater aquarium as part of the treatment.

Reduce the water level, making it easier for your fish to move around.

Reduce the water flow coming out of the filter if it is set with a stronger current. 

If part of the fish body is exposed to air consistently because of the way it is floating, apply a stress coat to avoid sores’ occurrence. 

If your fish is having significant issues with movement, you can try hand-feeding them.

If none of the treatment options work for resolving swim bladder disorder in your fish, then, unfortunately, you are going to have to decide whether or not to have them put to sleep. 

Like any other pet, if you suspect that there is something wrong with your fish, you need to take them to the vet, especially if you are a beginner. You do not want to treat them for something they do not have because you are not sure. Even novice aquarists take their fish to the vet. Just because you have had fish for 20 years doesn’t mean you always know what is wrong when they start to act out of character. 

Before you even purchase fish for your tank, do extensive research on the species. Learn all of the ins and outs of their habits, their likes, and dislikes, purchase the highest-quality equipment and food that your budget will allow, and do not just put them in the tank and never pay attention to them.

Believe it or not, fish like attention, just like any other animal. If you just feed them and walk away and never really just sit and watch them, you will not know when something is out of character, and you will end up with dead fish. 


As I have stated in this piece and many others, fish is not something you just toss in a tank, feed every day, and ignore. They are pets! They like to be watched and paid attention to. If you do not know what the ideal characteristics and behaviors are, you will never know when something is wrong with your fish.

Having an aquarium is a big responsibility, and there is a lot involved. There is equipment to purchase that keeps your fish and your tank clean and healthy, and you have certain foods that you should never feed your fish. There is weekly and monthly maintenance/cleaning that needs to be done and other responsibilities. 

As I stated in the beginning, many diseases and disorders can affect your fish. Some of these can affect any species of freshwater fish, and some only affect certain species. Most of them have multiple treatment options, but there are a very select few that have no options at all.

You can avoid many diseases by simply keeping your water as clean as possible and paying close attention to what and how you feed your fish.

Relate Articles: 

Do I Need To Add Salt to My Freshwater Aquarium?
How Often Do You Change Filter Floss

5 Types Of Freshwater Fish Food


I'm passionate about fish pets and love sharing everything I learn about them.

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