Why Your Betta Fish Is Swimming Sideways (& What To Do)

As Betta owners, it’s our job to make sure our fish is always healthy. But no matter how careful we are, our beautiful Bettas will sometimes have problems that cause them to swim sideways. It could be because of many reasons, and it’s hard to say which one it is for sure!

If you want to learn more about Bettas’ peculiar behavior, this article will tell you everything you need to know about Bettas that swim sideways. So, keep reading!

Key Takeaways:

  • Betta fish may swim sideways or exhibit strange behaviors due to various factors such as water quality, temperature, and health issues.
  • Tips for addressing Betta fish swimming sideways include maintaining a clean tank, transferring sick fish to a separate aquarium, minimizing water current, adjusting water temperature gradually, providing a larger tank, checking water chemical levels, and using medications if necessary.
  • Betta fish swimming in circles can be attributed to their natural behavior, territorial behavior, parasite infections, ammonia poisoning, stress, whirling fish disease, and swim bladder disease.
  • Proper care, including maintaining water quality and temperature, can help keep Betta fish happy and healthy, reducing the likelihood of them swimming sideways or exhibiting abnormal behaviors.

Why Is Betta Fish Swimming Sideways After Water Change?

Betta fish are popular with people who are just starting to keep fish because they have interesting personalities, pretty fins, and high spirits. They also like to swim, float, or lay in weird ways in their tanks. But if they swim in a strange way after a water change, it could mean that something is wrong. Here’s a list of the most common reasons why Betta fish swim sideways after a water change.

Reason for Betta Fish Swimming SidewaysWhat to Do
Excessive Water ChangeAvoid excessive water changes to prevent ammonia buildup.
Too Much Chlorine in the WaterEnsure you treat tap water with a water conditioner before adding it to the tank.
Insufficient Water ConditionerUse an adequate amount of water conditioner to remove harmful substances.
Dirty AquariumRegularly clean the tank to prevent ammonia levels from rising.
Temperature ShockMatch the water temperature when changing water to prevent shock.
Water Is Too WarmMaintain the water temperature between 78-80°F (25.5-26.5°C).
Water Is Too ColdKeep the water within the preferred temperature range for Betta fish.
Lack of Oxygen in the WaterEnsure sufficient oxygen in the tank with aeration and surface movement.
Fish Is in ShockIdentify and address the cause of stress or shock in the aquarium.
Swim Bladder ProblemsMonitor your Betta’s feeding habits and adjust their diet if needed.

1. An Excessive Amount of Changed Water

If a Betta fish acts strangely, like swimming sideways, it could be because there is too much nitrate in the water, which is bad for the fish. The level of nitrate in the water goes up when too much water is changed, which disturbs the biofilm in the aquarium and causes ammonia levels to rise.

2. Too Much Chlorine In The Water

Most of the time, inexperienced aquarists poison their fish by putting fresh tap water in that hasn’t been treated in the aquarium or by adding a lot of untreated chlorinated water to their tank during a water change. Too much chlorine in an aquarium can actually hurt a fish’s gills, which leads to bigger problems that end with the Bettas swimming sideways.

3. Insufficient Water Conditioner

When there wasn’t enough water conditioner in the water used to change the water in the aquarium, it couldn’t get rid of the metals and chlorine in the water or break down the chloramines. This means that the water still has minerals that aren’t good for the Bettas. If the water is still used in the aquarium, it can make the Bettas swim sideways without control.

4. Your Aquarium Is Still Dirty

Cleaning the water tank often is a good idea. Just make sure to get rid of the fish waste when you change the water to keep the ammonia levels from going up and turning into nitrate, which is bad for the Bettas. Making it less likely that the fish will swim sideways.

5. Temperature Shock

Sometimes, when we change the water in an aquarium, we put colder water into the old warm water. This causes the Bettas to go into shock, which makes them swim sideways. To avoid this, make sure the water temperature of the new water when you change the water and the old water inside the aquarium is the same.

Close up of blue half moon Siamese fighting fish in a fish tank

Why Are Betta Fish Swimming Sideways on Top of Tank?

It is awful to see our favorite Betta fish swimming in a way they aren’t supposed to. When the fish starts swimming in strange patterns, it could be an indication of a bigger problem. To treat our Bettas, you need to know why your fish could be acting like that. In this article, we will give a couple of reasons why your Bettas are swimming sideways on top of the tank.

1. Water Is Too Warm

Like every other fish, Betta fish prefer a certain water temperature. They prefer to live in temperatures between 78 and 80 degrees Fahrenheit (25.5 to 26.5 degrees Celsius). If the water in your aquarium gets too hot, you might see Betta fish float on top of the tank and swim sideways because they are cooling off by getting closer to the cold open air.

2. Water Is Too Cold

Bettas come from warm, tropical climates, so they don’t do well in colder places. When it gets too cold for the fish to handle, they tend to get pretty close to the heat source to get warm. So, floating to the top of the tank and lying sideways will expose the fish to the light in your aquarium and warm itself up.

3. Lack Of Oxygen In The Water

If your Bettas are still swimming to the top of the water in your aquarium even though the temperature is right and the tank is clean, it might be because there isn’t enough oxygen in the water. Bettas belong to a group of fish called “labyrinth fish.” These fish can get some of the air they need from the surface, which is why you might see your Betta swim sideways on the top of the tank from time to time.

4. Fish Is In Shock

There are many different things that can cause shock to a Betta. It could be from a long period of stress, a serious injury, illness, or a sudden change in water. When this happens, they usually rise to the top of the tank and lie sideways. When this happens, make sure to act quickly because shock in fish can be life-threatening.

5. Swim Bladder Problems

The swim bladder is a specialized organ that helps fish control how much they float around in the water. So when this special organ isn’t working right, it can cause problems to the Betta’s ability to swim, which then makes the Betta swim sideways on the top of the tank.

6. The Spawning Season Has Started

Your Betta could also be getting ready to spawn, which could explain why it’s swimming sideways on the top of the tank. When it is mating season, male Bettas prepare by making a bubble nest which is done by taking air from the surface and grouping them together with its own mucus. 

7. Fish Is Just Resting

Sometimes, Bettas can just be resting and floating on the surface. This doesn’t necessarily mean that something is wrong with it. If it is not doing this too often or for more than a few minutes at a time, it is probably just taking a break from swimming around in the tank. 

betta care facebook group

What to Do When Betta Fish Is Swimming Sideways

In many fish tanks and aquariums, it’s common to see a Betta fish lying on its side. And it is always a scary sight that we, as aquarists, always worry about. But if you think your Betta’s erratic swimming could be caused by something else, we have made a list of things you can do to help your fish.

1. Maintain a Clean Tank

To stop your Betta from swimming sideways, the water in a tank should be cleaned at least once a week. This helps get rid of the deadly substances that have accumulated in the water. After every cleaning, put in the right amount of dechlorinated water at the right temperature to avoid making your Betta’s condition worse.

2. Transfer Fish To A Hospital Aquarium

If your Betta has started swimming sideways, it could mean that it’s sick and you should put it in a separate aquarium unless it is the only fish in its tank. By doing this, you can keep the sick Betta away from the healthy Bettas and stop the disease from spreading to other fish. This will also help you see how your sick Betta is doing, but make sure the conditions in both aquariums are the same to cause as little stress as possible.

3. Minimizing the Water Current

The fins of Betta fish are bigger than those of most other fish. Because of this, they swim much more slowly than other fishes. If your Betta has started swimming sideways, slow down the water flow in your aquarium, so your fish doesn’t get tossed into driftwood and plants.

4. Heat Up the Water 

When you have Bettas, you have to be extra careful about how hot or cold the water in your aquarium is. These fish prefer water temperatures around 78 and 80 degrees Fahrenheit to keep them healthy and can help them back upright from swimming sideways. But before you adjust the water temperature, always keep in mind that it should be changed slowly because if you don’t do this, the fish’s condition will worsen.

5. Give Bettas A Large Tank

Betta fish can live on their own if they have a bigger tank. The reason why your Betta fish are swimming sideways is that they often have to lay next to their leftover food or their own waste because they don’t have enough room. If this goes on for a long time, it could lead to fungal infections and other health problems.

6. Check The Water Chemical Levels

You have to check the levels of chemicals in your tank water on a regular basis, especially when your Betta has started swimming sideways. When this happens, it usually means that the water in the aquarium has alarming levels of nitrate and ammonia, and it is a good idea to detect the problem early on. Just make sure that you improve the water quality slowly because if you make the change too quickly, your Betta fish might get shocked.

7. Use Medications

Curing the disease might be possible if your Betta has started swimming sideways due to an illness, so you should always research about the specific condition your fish is facing and consider using medications that have been proven to help with it. But make sure to use the medication correctly and never overmedicate, as this can harm your Betta’s health.

For example, if your Betta is suffering from Swim Bladder Disease, you can add epsom or aquarium salt to the tank, or use antibiotics.

Here’s a reddit user also sharing a video of his Betta swimming sideways:

Why Is Your Betta Fish Swimming in Circles?

Betta fish are usually resilient as long as you give them the right tank, keep their water clean and free of toxins, and feed them a healthy, well-balanced diet. But if your betta fish is swimming in circles, that could mean something is wrong, or your fish is just super healthy. Read this article to learn some of the most common reasons why your betta fish swim in circles.

1. Swimming In Circles For Fun

Many fish keepers and aquarists think that Bettas are lazy, but given the right conditions, they can be very active and playful. You can see them swim in circles, moving moss balls around, dancing around their tank, or showing off their tails. This means that your bettas are healthy and well taken care of.

2. Territorial Behavior 

Territorial behavior is common in fish, and bettas are especially known for it. A fish will swim in circles around the edge of its territory to tell other fish to stay away. To keep bettas happy, it’s a good idea to give them live plants and decorations they can use as hiding places.

3. Parasite Infections

When parasites live on a fish, they make the fish feel uncomfortable. Fish naturally rub against things in the aquarium to get rid of parasites. This could be why your Betta is swimming in circles around your tank.

4. Ammonia Poisoning 

If your betta is swimming around in circles, it might be sick from too much ammonia or because the conditions in its tank are getting worse. Some of the signs of ammonia poisoning are swimming in fast circles, clamped fins, gills that are bright red or black, gasping at the surface, being tired, not wanting to eat, and breathing quickly.

5. Stress 

If your betta keeps trying to swim in circles, it may be trying to tell you that it is feeling stressed. This is usually caused by changes in the tank’s environment, like putting in a new fish or introducing new aquatic plants or decorations. Keep in mind that stress weakens the Betta’s immune system, making it more likely to get parasitic and bacterial infections, and it is why it’s crucial to fix whatever is causing your Betta to be stressed.

6. Whirling Fish Disease

Whirling fish disease is commonly found in the wild, but it can also affect most aquarium fish, even our beloved bettas. It is an infection caused by a parasite that affects the bones and cartilage of a fish and makes it swim in circles or spirals. Unfortunately, these physical signs of infection don’t usually show up until 35 to 80 days after our fish has been infected, making it almost impossible to cure the fish, which means that the fish will eventually die.

7. Swim Bladder Disease

Despite its name, swim bladder disease isn’t usually caused by diseases but more by Irregular feeding habits and digestive issues. When this happens, digestive problems like bloating and constipation put pressure on its swim bladder, making it harder to control. If a fish has swim bladder disease, it may swim around in circles because it struggles to go in one direction. 


Can Swimming Sideways Be Dangerous to Your Betta?

The severity of the disease and the chances of survival depend on the root causes of the illness. If the problem is caused by poor diet or constipation, the Betta is likely to recover quickly. However, if the disease is caused by microbiological or parasitic factors, the chances of survival may be low. 

Is Swim Bladder Disorder Transferable?

Swim Bladder Disorder cannot be transmitted from one Betta to another. However, if a pathogen or bacteria is the primary cause of the condition, it may spread and infect other species in the aquarium. Therefore, it’s crucial to maintain a clean environment in the aquarium.


Taking care of a Betta as a pet can be hard, but it’s not impossible if you know what to do. If it’s swimming sideways in the tank or floating on top of the water, this could be a sign of something more serious. It could be because of their natural behavior or instincts, too much ammonia in their bodies, or a lot of stress. Make sure your Betta is swimming in nitrate-free water that is at the right temperature and that the tank is cleaned regularly to avoid this from happening. By doing these things, you’ll keep your bettas happy and healthy, and they’ll probably thank you for taking care of them.


About the author

Hey there! I'm Antonio, the passionate owner and chief editor of Betta Care Fish Guide. With over half a decade of hands-on experience, I've become your go-to expert for all things betta and tropical fish.

Over the past 5 years, I've not only kept bettas and other tropical fish but also connected with a diverse network of hobbyists, seasoned fishkeepers, and even veterinarians.

Now, I want to help other beginner fish keepers who had the same questions as me when they were just starting out! So they can save themselves a ton of time and keep their fish happy and healthy!