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Why Is My Betta Fish Standing Straight Up

Betta fish are commonly known as a “starter pet” as people think they are easy to take care of. However, if you’re unaware of the proper steps needed to take care of a betta, problems can arise in the tank faster than you may notice it. Observing the fish’s behaviors is the best way to discover if there may be a problem. 

Abnormal behaviors such as swimming vertically can be caused by many factors such as swim bladder disease, constipation, or tank conditions. 

Read on to learn how to recognize this behavior, determine the cause, and fix the problem.

Four Common Reasons Why Your Betta Fish is Standing Straight Up

There are many possible reasons why your betta fish is swimming vertically or “standing up”. There are ways to determine which possible reason it may be, and some are more difficult than others.

Swim Bladder Disease

One reason your betta fish may be swimming vertically is that they may have developed swim bladder disease. A bacterial infection can cause this due to poor water conditions or simply an injury. The swelling in the stomach is caused by a gas build-up which affects the betta’s ability to swim normally.

Recognizing swim bladder disease is simple; the fish may have injured itself, or the problem could be coming from the water conditions or the size of the tank. If your levels are normal and you have an acceptable tank size, check the underside of your betta to see if his stomach is swollen. This is due to a gas build-up causing the fish to float and preventing it from swimming normally. 


Keep in mind that abdominal swelling can also be caused by constipation. Constipation in fish is usually caused by overfeeding or an irregular feeding schedule and will only affect a fish’s ability to swim if it is in a critical state.


To determine whether the cause of the fish standing straight up is constipation or swim bladder disease, monitor the fish’s waste. If it is sticking to the fish rather than dropping off and sinking, it may be constipation. Noticing these symptoms and acting quickly is imperative to saving your fish from fatality. 

Size of the tank

Betta fish usually come in a small container when you purchase them, contributing to the misconception that they can survive in a small space. Until recently, the minimum tank size for a betta was one gallon, which is a tiny space for one fish to thrive. For other freshwater aquarium fish, it is recommended that you only have one two-inch fish per 5 gallons.

The best size tank for your betta fish to flourish and grow would be no less than 5 gallons. This allows enough room for your betta to swim around and not feel trapped in a small environment. Having a smaller tank contributes heavily to poor water conditions. 

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It would be best to clean it more often due to the heavy waste build-up that occurs faster in a smaller environment. If you’re cleaning the tank regularly and your fish is still standing straight up, it might be a sign that your betta needs more space.

Poor water conditions

If there is no abdominal swelling present and your tank is the correct size, the reason your fish is swimming vertically can simply be from the conditions of the water. 

Elevated levels of chemicals such as ammonia and nitrates could cause the standing behavior in betta fish, as they can only tolerate chemical levels lower than 50 ppm. Suppose your betta is displaying this upright behavior. In that case, it is crucial to act quickly because the chemical levels will only impact the fish’s behavior if it has reached 100 ppm, which is double what the normal level should be.

Levels to Check

Understanding the water chemistry in an aquarium is essential to housing a safe environment for your betta. The breakdown of waste is a biological cycle, starting with releasing ammonia from fish waste, eventually converting it into nitrates by the good bacteria. It is normal to have low levels of ammonia and nitrates, but if your fish is swimming upright, ammonia and nitrates are the critical levels to check.

Ammonia emits from leftover food and fish waste, or if it is a sudden increase, one of your fish may have died. Due to this, there is a build-up of nitrates caused by the prolonged presence of fish waste and leftover food. Another contributor is a lack of live plants, as they use these chemicals as a source of food. 

It is important to check your ammonia and nitrate levels, as elevated levels can cause fish to go into shock or develop ammonia or nitrate poisoning, causing them to swim vertically. You can purchase specialized kits online or in pet stores that test the levels of nitrates and ammonia and let you know if it is at a dangerous level.

How to Help Your Fish

Once you notice your fish standing straight up, you must quickly determine the source. It is important to act fast, as it could be detrimental to your fish’s well-being if not taken care of immediately. The information presented below will give fish owners an understanding of the problem and how to fix it.

Lowering elevated chemical levels

The primary source of many problems that arise in fish is due to the water conditions. The first step after noticing your fish swimming upright is testing the water levels to determine if there are elevated chemical levels in the water.

It is not uncommon to find chemicals in your tap water, and it is essential to test your water before filling your tank or even doing water changes. Products such as tap water conditioners can help remove harmful chemicals from the tap water, but if the levels are abnormally high, you may want to consider another water source.

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If there are unusually high levels of chemicals present in the tank, perform small water changes over the course of 24 to 48 hours to slowly lower the concentration to a normal level. Test the baseline levels before the water changes and after each water change to monitor the decrease. Fish can only tolerate up to a 5% water change every couple of hours, so be sure that you’re leaving enough time in between water changes to prevent your betta from going into shock. 

Most pet stores sell tools such as a gravel vacuum that will target the removal of waste stuck in the gravel. Removing water from the top of the tank is not as effective, as the source of the chemical emissions that come from leftover food and fish waste that settles in the gravel. Using this tool to perform the water changes will ensure you’re removing the harmful source.

Tank size and overcrowding

If there is no problem with the water levels, consider your tank size and the number of fish. Lack of space to swim and overcrowding causes aggression and lack of oxygen, leading to the standing behaviors. 

You should only have one, two-inch fish per 5 gallons. So, for example, if you have a 15-gallon tank, you can have a maximum of 3 fish. Overcrowding leads to stress and conflict, and purchasing a larger tank will help relieve some stress from your fish, giving them enough space to separate.

Swim Bladder Disease treatment

The fastest way to cure swim bladder disease is to purchase treatments, such as Melafix, to heal the bacterial infection internally. In addition, do not feed your fish for at least a couple of days. 

If there are other fish in the tank that you need to feed, consider moving the sick fish to a different tank, or placing an aquarium divider between the fish. This will allow you to feed your healthy fish while preventing the sick fish from eating.

Swim Bladder Disease treatment

Although this disease is not contagious, you want to keep a calm environment for the sick fish to recover. Conflicts between fish can cause stress and aggression, so keeping them separated during the recovery process is essential.

Constipation treatment

Treating constipation in your fish is very simple, and fasting is the best recovery for a fish dealing with constipation. Please do not feed your fish their regular food for at least a couple of days until you notice their waste is normal.

An alternative treatment to fasting would be feeding your fish foods that are high in fiber, such as peas or brine shrimp. This will help speed up the digestion process and aid in their recovery. Monitor the standing behavior closely as you provide treatment.