Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Betta Fish Swimming Erratically – 12 Potential Reasons

Sarah Psaradelis

By Sarah Psaradelis

betta fish surface of water looking up

If your betta fish is displaying an unusual behavior of erratically swimming around the tank, it is typically a cause for concern. Betta fish are not good swimmers due to their long and flowing fins that do not help with their agility in the water. There as several different reasons your betta fish may be swimming erratically throughout the water. This behavior is usually accompanied by other symptoms that are easily identifiable. Getting to know the natural behaviors of your betta fish is a good idea so that you can catch any issues during an early stage.

There may be different reasons as to why your betta fish is swimming erratically through the tank, whether they are doing it out of nowhere display it as a frequent behavior.

aquarium plant divider

How to Tell If Your Betta is Swimming Erratically

Abnormal swimming patterns with your betta fish are the first sign that something is bothering your fish. The betta may swim in circles, drift in the current, or swimming into things. These are all warning signs that there is something very wrong with your betta and treatment should be done immediately.

Your betta fish may begin to swim unnaturally fast in an irritated manner around the tank. They will generally bump into other objects in the tank or continuously swim into the glass. Scratching against objects typically means that there is a parasite on their body that is irritating them, and they use erratic swimming to relieve their symptoms. Betta fish are slow and gentle swimmers which makes this new erratic behavior alarming. A fish that is suffering from severe health problems will also swim abnormally.

If your betta fish is twitching while zooming around the tank and purposefully bumping into things, you may be dealing with a potential parasite or fungal outbreak in the tank.

betta fish in aquarium
Image Credit: ivabalk, Pixabay

12 Reasons Your Betta Fish is Swimming Erratically

Each reason has specific symptoms that come with the diagnosis. This makes it easier to compare your betta’s symptoms and determine what the main cause of the erratic behavior is.

1. Parasites

Parasites can affect several different areas of a bettas body. They typically irritate the skin of the fish and cause major discomfort. The affected area may also become swollen or red and if you look closely, you may see where the parasites are eating away at the skin. This is common if you recently got your betta, or if you added in a new fish that carried the specific type of parasites.

2. Ich

Ich causes many white spots to develop over the skin of the betta fish. It affects both the body and fins. Do not confuse ich with epistylis which is a much deadlier disease that requires professional treatment. Ich will cause your betta to swim erratically and rub against objects in the tank to try and get rid of the disease.

3. Fish lice

This becomes a very prominent health issue that causes the betta to swim out of control because it is uncomfortable. They will typically dive into the substrate in an attempt to stop the itch.

sick betta fish
Image Credit: Wirestock Creators, Shutterstock

4. Flukes

Flukes are a common but deadly disease that should be treated as soon as you notice any symptoms. Flukes do not usually show symptoms right away, but your betta will scratch along objects in the tank. You get different types of flukes such as gill or skin flukes. Gill flukes can cause gill discomfort and make breathing difficult.

5. Anchor worms

Anchor worms hook onto the skin of the betta fish and start sucking the blood from the fish. They can also bury into the skin and cause bumps or large welts to appear across the body of the fish.

6. Stress

If your betta is stressed from a small aquarium, it will swim erratically through the water out of irritation. Small aquaria like bowls, bioorbs, and tanks under 5 gallons can cause this behavior to occur. As a last resort, the betta may swim fast towards the top of the tank and jump out to escape their stressful environment.

Image Credit: yin8003211, Pixabay

7. Nervous system disorders

This will cause fast whirling or circling behaviors. They may be constant or only occur a few times a day.

8. Poor vision

This is associated with vision issues like cataracts or corneal damage that can be both hereditary and the result of a nutrient deficiency. If there is any excess gas in the water or fluid retention in the betta’s body can cause exophthalmia. There is also the possibility that a parasite has made its way to the eye and started to eat away at it. This will cause the betta to swim blindly through the water and feel off-balance due to vision loss or damage.

9. Neurological damage

If certain strains of bacteria or parasites infiltrate the brain tissue, they can cause neurological damage. Your betta can also develop neurological problems from injuries to the head or spine.

red betta fish in aquarium
Image Credit: 13683717, Pixabay

10. Hypoxia

This is caused by poor oxygenation and poor water quality. Once the betta has been deprived of proper oxygenation in the water, they will start to develop brain damage and swim erratically.

11. Poor water quality

High levels of ammonia, nitrite, or nitrate can burn the betta fish and they will swim around the tank or attempt to jump out to relieve their discomfort.

red betta in aquarium
Image Credit: MANU PARADY, Shutterstock

12. Nutritional deficiency

Lack of fiber in the betta fish’s diet can cause mobility problems of the intestines as the result of air accumulating in the swim bladder organ which can cause the betta to float or swim abnormally around the tank.


Aggressive Swimming

Sometimes your betta can see its reflection in the glass which will cause them to flare and chase the reflection. This sometimes cannot be helped and will cause the betta to become stressed or tired from constantly flaring. Adding in lots of cover in the form of live plants can help to divert your betta’s view of its reflection.

Treatment Plans

If you think that your betta is swimming erratically because of a disease or parasite, then they should be treated immediately using a high-quality medication from your local fish store that is tailored towards the specific symptoms your fish is experiencing. Brain disorders can be made easier by removing hard or sharp objects from the tank and placing lots of live plants against the glass to soften the blow if they swim into the glass.

Image Credit: gogorilla, Shutterstock

What Are Betta Fish Zoomies?

This is not usually a cause for concern and is displayed as a betta fish swimming fast towards you because they identify you as a food source. This shows that they are excited and know that they are going to be fed. Zoomies are not a form of erratic swimming, however, they do swim fast toward the source of excitement and the form in which they swim is normal.

aquarium plant divider


A betta swimming erratically can be both good and bad behavior. Determining the cause of the behavior is going to be your best option. Only treat a betta for swimming erratically if you have found the cause of the behavior, whether it is from a parasite or an internal problem.

We hope that this article helps you to determine why your betta fish is swimming erratically and how you can deal with the specific issue that is causing this problem.

Featured Image Credit: Ivabalk, Pixabay

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database