Why My Betta Fish is Laying On One Side (What to Look For)

by Kevin

Male betta fish lying on side at the bottom of an aquarium.

Seeing your betta fish swimming sideways is concerning. While swimming sideways or resting near the bottom of the tank can be part of normal betta fish behavior, it can also be a sign that your betta needs medication and clean water. This article will explain what to look for and what you can do.

Is your betta fish lying on the bottom of the tank or struggling to swim?

First, observe your fish closely and determine if your betta fish is experiencing any of the following:

  • 1) Noticeable lethargy
  • 2) Loss of appetite for multiple days
  • 3) Discoloration (looking pale)
  • 4) Flicking against décor or rocks
  • 5) Bloating
  • 6) Trouble swimming
  • 7) Heavy breathing or gasping
  • 8) White spots or fuzz on fins or body
  • 9) Swimming sideways or upside down
  • 10) Fins that appear to be rotting away

If your betta fish is experiencing any of the above, he or she may be battling a handful of issues that commonly affect bettas.

If your betta fish is lying sideways on the bottom of your tank or on some decoration or plant leaves, it’s possible that he or she is simply resting.

But, if your betta fish remains on the bottom of the tank for multiple days and seems to have trouble swimming, he or she may be dealing with something more serious.

The first things to check when you notice that your betta looks ill or sluggish are:

  • 1. Water Quality
  • 2. Water Flow
  • 3. Temperature
  • 4. Damage to your fish

Even if the water looks clean, the ammonia level may have spiked up due to decaying food or a build up of waste.

Test your water with or bring a cup to a local fish store so they can test it.

Do a 50% water change and test while you wait to get the test results.

If your betta fish looks healthy but seems to stay in one part of the tank, check to see if your filter is too powerful.

Betta fish are not strong swimmers and will become tired and lethargic if water flow is too strong in the tank.

But, If your water flow is minimal, and your betta continues to swim sideways along the gravel, your fish may be suffering from a swim bladder malady (which is discussed more below).

Betta fish are tropical fish so make sure you the water temperature is between 74-80 degrees Fahrenheit (23.3-26.7 Celsius).

At lower temperatures, betta fish have trouble digesting food properly and fighting off infections.

Another possibility is that your fish is battling a disease or infection.

If your fish is gasping for air, lying on his or her side, and unable to move, a fungal or bacterial infection may be the issue.

Check for sores, bulging eyes, white spots, fuzzy areas, fin rot, or other signs that your betta may be fighting a disease.

What You Can Do to Help Your Sick Betta

Sick betta fish.

1) Provide a Clean Tank

A huge contributor to betta illness is a dirty tank.

If a betta is fed frequently but does not receive regular water changes, nutrients and waste build up in the bettas tank and allow bacteria, ammonia, and even parasites to thrive.

So, if your betta is ill, move your fish to a quarantine tank and thoroughly clean his old tank.

If your betta does not recover after entering a clean tank, medication may be necessary to help your fish fight off a fungal infection or other malady (more info on medications is provided below).

2) Provide a Larger Tank

Providing a larger tank is a quick way to have a healthier fish.

In a small cup, bowl, or vase, waste collects directly below a betta and pollutes the water more quickly than a tank with more water volume and a filter.

Bettas in big box pet stores are often lying on their side in their own waste and uneaten food.

This is not healthy for the betta and may lead to a fungal infection or other disease.

A 2.5 gallon tank is really the minimum for a betta fish, but only if you are experienced and provide consistent and frequent water changes.

While bettas certainly survive in smaller tanks and may live in smaller areas in the wild, domestic bettas are healthier and live longer in larger tanks because water conditions and waste are much easier to control in larger tanks.

5 gallon tanks are my favorite size for betta fish.

A 5 gallon tank provides enough room for your betta to exercise while also giving you some room to aquascape the tank.

If you want to learn more about aquascaping a betta fish tank, check out my article on designing a dragon stone aquascape for betta fish.

3) Keep a Betta First Aid kit

Keeping betta medication on hand is a smart idea because pet stores often do not carry betta specific medications or may be out of stock.

The quicker you are able to treat your betta’s disease, the higher the chance that your betta will recover.

Types of Betta Fish Medication

Most Betta medication can be found online, but if you don’t have betta medication on hand and need some ASAP, then look for one these at your local pet store:

1) Bettazing

2) Bettamax

3) Kanamycin

4) Tetracycline,

5) Amplicillin

6) Jungle Fungus Eliminator

7) Maracin 1

8) Maracyn 2

Natural Betta Fish Medications Include:

1) Melafix

2) Aquarium Salt

3) Indian Almost Leaves

I used all three of these to successfully treat my betta’s cloudy eye (bacterial infection), which you can read about here.

Even if you are not entirely sure what is making your betta sick, treating your fish with a medication like Melafix over the course of a week may give your fish a fighting chance.

Treating a Sick Betta Fish

You may be thinking that you are no fish doctor. Well, neither am I, but don’t be intimidated by the various medications that exist to help your fish.

First, you are going to diagnose your fish.

Then, you are going to pick the best medication for your betta’s specific illness.

But, before you dose any medication, if your betta tank has plants, or you have snails that you want to keep, it’s important that you put your betta into a different tank, a quarantine tank.

Doing so will prevent the medications from killing your plants or favorite invertebrates.

Let’s take a look at some diseases that may explain why your betta is laying on it’s side on the bottom of the tank.

1. Fungal Infection

Signs: your betta may look noticeably paler and lethargic. Clumped up fins or cotton-like patches on your betta’s body are also signs that your fish has a fungal infection.

Treatment: First, start by quarantining your fish.

Fungal infections are highly contagious and can easily spread to the tank’s other inhabitants.

If your betta lives alone in a planted tank, you may still want to quarantine your fish in a different tank to prevent any medications from harming your plants.

Once your betta is quarantined, administer an anti-fungal treatment in the appropriate dose.

Salt for fungal infections

While it might seem strange to add salt to a freshwater aquarium, adding aquarium salt (not table salt which may contain harmful additives) to your betta tank may help treat a fungal infection.

Adding salt is not without risk though; adding too much may harm your fish or your plants.

A general dosing guideline is one tablespoon per 5 gallons.

Use common sense and do your own research before attempting to add aquarium salt to your betta tank, and do not forget to do follow up water changes once your betta is feeling better.

Bettazing or Bettamax For Fungal Infection

Adding these to your infected betta tank over a period of at least three days should dissolve any remnants of the fungus.

Be sure to do a water change after all remnants of the fungus have disappeared.

2. Tail or Fin Rot

Signs: Your betta’s fins appear to be rotting away.

While fin rot may not be the primary reason your betta is lying on the bottom of the tank, it is a nasty and potentially fatal disease that your betta can contract while in a weakened condition.

If your betta is lying on the bottom of his tank, make sure to do frequent water changes and vacuuming to prevent waste buildup.

If your contracts fin rot while already fighting off a different disease, his chances of survival are much lower.

Treatment: Fin rot can be treated by adding Ampicillin or Tetracycline.

You may also want to treat your tank with an anti-fungal.

Once your tank is back to normal, consistent water changes and vacuuming will help prevent future outbreaks.

3. Ich (white spot disease)

Ich (Ichthyophthirius multifiliis) is a protozoan and is actually present in most aquariums and ponds.

A healthy fish’s immune system wards off ich on its own, but a stressed or weakened fish is highly susceptible to ich.

Infrequent water changes, improper water temperature, and a poor diet may substantially weaken a fish’s immune system.

But, one of the biggest stressors on fish is being shipped in the mail.

The process of shipping and handling fish from fish farm, to wholesaler, to retailer, takes a big toll on a fish’s immune system.

Ich is highly contagious and the most common cause of fish deaths.

Informing yourself about Ich and how to treat it will vastly improve the chances that your betta or other fish will live.

Signs: If your betta is covered in white spots and no longer wants to eat, ich is likely the culprit.

Treatment: To treat ich, quarantine your betta in a different tank, and raise the temperature to about 80 degrees Fahrenheit.

Then add formalin or malachite green.

Maintain the tank at 80 degrees for 48 hours and monitor the condition of your fish.

Again, quarantining your fish is important because ich is highly contagious.

4. Velvet

Velvet shows up when a tank has not been properly treated with water conditioner or salt.

Signs: If your fish is trying to scratch itself on aquarium décor or rocks, has lost interest in food, and holds his fins tightly against his body, your betta may be suffering from velvet.

Shine a light on your fish and look for a light gold or rusty film over its scales.

Treatment: cleaning the tank and adding BettaZing to the new water will help eliminate velvet.

5. Pop-Eye

If your fish has a bulging eye, it likely has pop-eye.

Signs: A single cause of pop-eye is not known, but testing your water and cleaning the tank should be the first course of action if you notice a bulged out eye on your betta.

Sometimes pop-eye is treatable and other times it is permanent.

Treatment: If your fish has pop-eye, test water conditions immediately.

If water conditions look ok, treat your betta with a medication intended to kill gram positive bacteria or use a medication that specifically lists “cloudy eye” or popeye on the bottle.

Consider treating with Maracyn or Maracyn II.

Follow the directions on the medication and performing at least 30% water changes for the about 4-5 days in a row after your betta’s eye gets better.

This should bring your tank back to healthy conditions.

6. Dropsy

Dropsy is not a specific illness, but rather a term used when your fish’s stomach swells, causing it’s scales to protrude sideways.

Signs: Swollen, bloated stomach, scales sticking outward rather than flat against the body.

Treatment: Dropsy is a sign that your betta can no longer regulate his or her fluids.

Dropsy will be fatal if not caught early on, but it can be cured with aquarium salt and medication.

But, early signs of dropsy are difficult to diagnose.

Dropsy is not contagious, but it is likely a sign that water conditions are not optimal and should be tested and changed.

7. Swim Bladder Disorder

Anatomy of fish; swim bladder location.
Anatomy of a fish illustration

If you have kept fish for a while, you may have experienced or heard of the dreaded swim bladder disease.

This condition affects the swim bladder of a fish, which helps the fish stay buoyant underwater.

Sadly, this is one of the more common conditions that affects betta fish.


1. Floating at the surface

2. Lying at the bottom of the tank

3. Trouble swimming

4. Bloated stomach region

5. Swimming upside down

What is swim bladder disease?

Swim bladder disease or swim bladder disorder is a condition where a fish is unable to properly float or sink.

In fact, swim bladder disease is not a disease at all, but rather a buoyancy problem.

In medical terms, the fish is suffering from either positive buoyancy or negative buoyancy.

Positive buoyancy means your fish floats to the surface and has trouble staying underwater.

This is a problem because a fish’s skin/scales are coated in a mucus membrane, which becomes ineffective when exposed to air for a long period of time.

This can lead to the fish developing skin infections and other issues.

Negative buoyancy is the opposite; your fish sinks and typically stays near the bottom of the tank.

This also carries health risk for a fish as waste tends to build up at the bottom of a tank.

What causes swim bladder disease?

Swim bladder issues can occur for a variety of reasons, including:

1) Infections

2) Water Quality

3) Genetics

4) Feeding and Digestion Issues

According to Aquatic Veterinary Service, the primary cause of swim bladder disorder in the Koi and Goldfish they treat is poor water quality.

In fancy goldfish (the ones bred to look unique), “structural deficiencies” in the fish are also a big contributor to swim bladder issues.

In other words, the genetics and prolific breeding of fancy goldfish has contributed to swim bladder problems.

Goldfish also develop swim bladder issues because they love to suck food in at the water’s surface.

This can cause air to enter the fish’s swim bladder, making it more buoyant and less able to swim properly.

While betta fish are not mentioned, I imagine that the issues mentioned above would be the same.

Betta fish are often kept in relatively small containers and tanks where water quality can quickly degrade and become toxic.

Betta fish also like to gulp food from the water’s surface.

And, betta fish, like goldfish, are bred frequently and in extreme numbers.

Selective breeding of betta fish has given us the many amazing colors and fin shapes that now exist.

But, the downside is that some fish with structural deficiencies, or genetic problems, also breed, and may produce offspring that are prone to developing swim bladder disorder.

So, the main point is that poor water quality and some breeding practices may lead to swim bladder disease.

If you want to reduce the chance of your betta getting it, keep your fish in a larger tank and perform frequent water changes.

If you are in the market for a betta fish, try to find a reputable breeder (rather then buying from a big box store), or buy a wild type betta fish.

How to Treat Swim Bladder Disease

I am not a veterinarian so if your fish looks like it needs medical care, please consult a vet in your area.

From my research, the best way to treat swim bladder issues is to figure out what caused the swim bladder to malfunction.

Because swim bladder issues can occur for a variety of reasons, including digestion problems, genetics, physical trauma, etc., you are best served by consulting with a vet who can give you a clear idea of what is ailing your specific fish.

That being said, betta fish can live a long life and happy life with swim bladder disorder.

Depending on whether your fish has positive or negative buoyancy, here are some things that have helped one of my bettas (he suffers from negative buoyancy):

1. Reduce the water level in your tank (for negative buoyancy fish)

Betta fish need to be able to come to the surface for air, and also tend to prefer eating at the surface of the water.

By lowering the water level in your tank, you reduce the distance your fish needs to swim to the surface.

2. Reduce Water Flow

Fish with swim bladder problems already have trouble navigating around, and a moderate current can tire and stress these fish out.

Consider replacing your normal filter with a sponge filter, produces almost no flow but still captures debris and oxygenates the water.

3. Use a Sinking Pellet Food (for negative buoyancy fish)

While a fish with negative buoyancy swim bladder issues may be able to swim to the surface and grab a bite of food, it takes that fish more energy and effort to do so.

Using a sinking type food pellet may help you keep your fish fed without your fish needing to burn extra calories to reach the surface.

4. Keeping the water quality pristine and the temperature between 74-80 Fahrenheit (23.3-26.7 Celsius).

Performing water changes will go a long way in keeping your betta fish healthy.

Water changes help remove toxin and waste buildup, which helps you fish avoid infections and other diseases while suffering from swim bladder issues.

Maintaining a temperature above 74 Fahrenheit (ideally between 78-80 Fahrenheit) is important because it helps with digestion, which can be a contributor to swim bladder problems.


Catching signs of disease early gives your betta fish a good chance of recovering quickly.

If you want to find out how I cured my betta’s cloudy eye with natural medication, check out my post here.

One of the best ways to help your betta fish is by keeping him or her in a cycled tank and performing regular water changes.

Aside from that, keep your betta’s water clean (get a filter), don’t over feed your fish, and have a betta first aid kit ready.

Keeping your betta in a tank that is 3 gallons or above (a 5-gallon tank is my favorite for a betta fish), with live plants, will also help your fish thrive rather than just survive.

And, don’t underestimate the power of water changes.

Even small water changes, performed on a consistent schedule, will drastically improve the health and lifespan of your betta.