Betta Fish Laying On Side: Causes And Solutions 

Jennifer Doll

Jennifer Doll


betta fish laying on side

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Have you recently looked in your aquarium to find your betta fish laying on its side at the bottom of the tank?

Though this isn’t expected behavior, it’s not necessarily a bad one either. There are a few reasons why your betta fish might be laying on its side, like age, sickness, or water quality, and it’s important to understand why.

Keep reading to find out everything you need to know about why betta fish lay on their side, if it’s normal, and what to do next!

Why Is Your Betta Fish Laying On Its Side?

Betta fish are not the most active fish, but laying on their side isn’t the most normal behavior either. 

A healthy betta fish will have bright colors and flowing fins. They should be relatively active within the water column and be interested in any food that is offered.

An unhealthy betta fish might have a loss of color, discoloration, or even show stress stripes. They also won’t be willing to explore their tanks and may lose interest in eating food entirely.

At the same time, a resting or sleeping betta fish may display the same signs. However, there are a few ways to tell a sleeping betta fish apart from a sick one.

There is usually no one reason why your betta fish is laying on its side. Some possibilities include resting, disease, illness, or poor water quality.


It’s true, fish sleep. However, they don’t go into a deep sleep like other animals but do experience a restful period when the aquarium lights go out.

Tropical fish will find a safe spot in the tank where they can take brief moments to stop swimming and relax. This is usually under a rock or behind plants, though it can be anywhere your fish feels most comfortable.

During this time, the fish may have irregular swimming patterns and may lose its color. A healthy betta fish will regain its color within the first few hours when the tank light is turned back on.

However, some bettas take this behavior to the extreme, which can be alarming. Some betta fish stop moving entirely, sometimes falling over themselves onto the substrate while they’re trying to sleep.

This can certainly look like something is wrong with your fish! However, it’s usually no cause for concern.

As long as your fish is only demonstrating these behaviors at night, then it’s relatively normal. If you find that your fish starts to appear raggedy or loses interest in eating, then there may be larger issues to address.

Betta Fish Disease And Illness

If you find that your betta fish is sticking around the bottom of the tank the better majority of the time, disease and illness are most likely the cause.

Betta fish are often kept in improper conditions, which could include a tank that hasn’t finished its nitrogen cycle or in a tank with other fish that bully and harass the betta. 

That being said, sometimes illness can happen on its own and it’s important to know how to take care of your fish in case of emergency.

Fin Rot

One of the most common causes of lethargic betta fish is fin rot. This can be caused by fungal or bacterial infections but is usually caused by poor water quality.

Fin rot causes the fins of the fish to clamp and tear, making it difficult and painful for your fish to swim. This will leave them resting on plants and decorations or even at the bottom of the tank.

The most common cause of fin rot is irregular water parameters. Usually, a series of regular water changes can help get your fish back to full health, though sometimes medication is necessary.


Parasites are most likely to show within the first few weeks of introducing a new fish to the tank. This includes ich, velvet, and flukes.

Depending on the parasite, your fish can develop white spots and lesions as well as secondary bacterial or fungal infections.

Parasites may also cause a loss of appetite and lethargy, while also making it difficult for your fish to breathe causing them to stay towards the surface of the water. 

Each parasite has a different treatment. First, identify the type of parasite you’re dealing with and treat it accordingly.


Sadly, betta fish are prone to becoming constipated. This can lead to discomfort, a swollen belly, loss of appetite, and lethargy.

Constipation is largely due to an improper diet but can also be a result of a lack of exercise. 

A constipated betta might not seem like a big concern but can become deadly if left untreated. A few ways to treat constipation include putting your betta fish on a pea diet, introducing Epsom salt baths, or intermittent fasting.

This condition can be difficult to identify at first but is relatively easy to treat.

Swim Bladder Disease

Swim bladder disease can look like constipation and is often the result of an untreated condition.

Fish with this disease are unable to regulate how they swim. The swim bladder is a lung-like organ that helps maintain buoyancy.

Once this organ is affected, the betta can experience difficulty staying upright in the water column, often leading the fish to swim sideways or upside down altogether.

The exact cause of swim bladder disease is unknown, though it’s thought to be a secondary outcome of most common diseases. In order to treat this disease, the primary conditions need to be treated first.

Tank Setup And Water Quality

betta fish laying on side

Another reason your betta fish may be laying at the bottom of your tank could be water quality.

As mentioned before, betta fish are commonly kept in incorrect tank conditions and water parameters. Each incorrect water parameter will have a different effect on your fish.

The ideal setup and water parameters for a betta tank include:

  • Minimum tank size: 5 gallons (18.9 L)
  • Water temperature: 78-80° F (25.6-26.7° C)
  • pH: 6.5-7.0

One of the biggest problems regarding water quality is a tank that is too small. Betta fish need a 5-gallon tank at a minimum. 

Though betta fish aren’t the most active swimmers and don’t need much extra space, a larger water volume makes it much easier to maintain water parameters. 

Not only can incorrect water parameters cause your fish to become lethargic, but strong currents and aggressive tank mates can also make your fish more reclusive and likely to stay towards the bottom of the tank.

With poor water conditions, your fish could also be experiencing ammonia or nitrite poisoning. Always remember to use a water conditioner to help keep your tank safe and clean. 

Ammonia Poisoning

Ammonia is deadly to fish. Even in small amounts, increased ammonia levels can chronically affect fish over time.

Ammonia poisoning is the result of dirty water or a tank that isn’t cycled. In a mature setup, ammonia is quickly converted by beneficial bacteria to less toxic forms of nitrogen, like nitrate. 

Nitrate then needs to be removed by frequent water changes and good tank maintenance.

In newly set up tanks, the beneficial bacteria aren’t established enough to complete this process. As a result, toxic ammonia levels stay in the tank water, making their way into the gills and organs of your fish.

This leads to physical internal and external damage for your fish as the tank water burns. This can definitely cause your fish to lay at the bottom of the tank or swim in front of a strong water current to try to get additional oxygen.

Even though betta fish are considered hardy fish for beginners, their tank still needs to complete the nitrogen cycle.

Nitrite Poisoning

Nitrite poisoning is similar to ammonia poisoning. Instead of directly burning your fish, nitrite causes a chemical reaction.

The chemical structure of nitrite allows it to bind to hemoglobin in blood where oxygen could otherwise bind. This causes low concentrations of oxygen in the blood, leaving your fish to suffocate from the inside out.

Nitrite poisoning is caused by nitrites being present in the aquarium water. This is the second phase of ammonia in the nitrogen cycle and is just as deadly.

Since fish are deprived of oxygen in these conditions, they will often become lethargic and lay at the bottom of the tank. When they have the energy, they may also swim in front of currents to try to take in more oxygen.

A good way to prevent this is by allowing a new tank to fully cycle and keeping up with daily tank maintenance.

How Do You Know If Your Betta Fish Is Dying?

Sadly, if your fish laying at the bottom of your tank, it isn’t a good indicator of its future. How do you know if it’s too late to save your fish?

A dying betta fish will be incredibly weak. They won’t be able to keep themselves upright and will often have faded colors.

For a few days prior, they may have a loss of appetite, be more prone to bodily injury, and display odd behaviors, like flashing, scratching, and labored breathing.

If your fish is lying completely on its side, breathing quickly, and getting picked at by other fish, it is usually too late.

However, if your fish is still making attempts to swim around your aquarium, then it may be time to move the fish to a quarantine tank and treat it aggressively.

If your fish is laying on its side and there are no signs of illness, disease, or poor water quality, then it may just be your fish’s time. Betta fish only live for about 2-5 years on average in captivity and there’s no telling how old your fish truly is when you bring it home.

A natural passing as your betta ages should be quick and painless. Your fish may still exhibit some loss of appetite and general lethargy, but there is nothing that can be done when the time comes.

Final Thoughts

It can be very concerning to see your betta fish laying at the bottom of the tank. This behavior is usually the result of a larger problem, like disease or poor water quality, and needs to be addressed immediately.

However, sometimes you may just have a lazy or sleepy betta with no underlying conditions. Even if that’s the case, continue regular tank maintenance and test parameters to ensure there is nothing wrong.

If you have any questions about why your fish is laying at the bottom of its tank, or related betta diseases and illnesses, please don’t hesitate to leave a comment below! 

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