Stressed Betta Fish? Here’s How To Help

by Aquarium Scoop | Last Updated: January 16, 2023

Stress in Betta fish often comes from environmental factors such as incorrect water parameters or a poor habitat setup that makes it feel unsafe.

In this guide you’ll learn:

  • How Can You Tell If Your Betta Is Stressed?
  • What Are Usually The Main Causes Of Stress?
  • How Can You Reduce Stress For Your Betta?
Stressed betta fish isolated in a tank

It’s better if you catch signs of stress early on so you can prevent it from affecting your Betta’s immune system. Stress often lowers the immune system making pet fish more prone to illness. Prevention of stress in Bettas is usually easy and is only a matter of good aquarium or tank keeping.

Signs & Symptoms Of A Stressed Betta Fish

It’s good to be familiar with your pet’s usual behavior so you’ll be able to notice any changes that can point to signs of stress. Stress will manifest as changes in behavior in most fish.

Strange or off behavior and lethargy

Any behavior that your Betta is showing that seems off or is unusual may be a sign that it is under stress, especially if it becomes lethargic or is less active. Check the common causes of stress listed below, especially your water quality conditions, to rule out any of these stressors. A sick Betta can show weird behavior and sickness is also a sign of stress.

Betta fish have a “labyrinth” organ that allows them to take gulps of air from the surface to help them survive in water that has low oxygen levels. If you notice your Betta fish gulping at the surface of the water a lot, then you may have very low oxygen in your tank’s water.

Loss of appetite

A sudden loss of appetite can also be a sign of stress. Perhaps your Betta feels too exposed or unsafe in its tank and therefore is not comfortable enough to eat properly. Fish will naturally be a bit skittish or wary of its surroundings as it feeds to check if there are any competitors that may be lurking. Make sure your tank has enough hiding places and is big enough for your Betta. 

Changes in the environment can also cause erratic feeding behavior. Fish will often try to conserve their energy if they notice something off in the water. Check if your water temperature is too low, causing the metabolism of your Betta to slow down and make it lose its appetite. 

Skittish swimming behavior

A sign that poor water conditions in their tank are causing your Betta some stress is skittish or darting swimming behavior. In the wild, if fish encounter a part of the water that has very low oxygen, for example, they usually swim away towards the surface where there is more oxygen. 

If you notice your Betta is swimming in a strange way, double-check your temperature, pH, oxygen, and even your filter. High levels of toxins (ammonia, nitrate, and nitrite) in the water may also be affecting your Betta. 

Erratic swimming behavior can also be due to aggressive or territorial tank mates. Make sure there’s ample space in your tank for all your pet fish to establish their own territories. Hiding places help alleviate territorial disputes as well. 

If your Betta is rubbing against rocks, gravel, or plants then maybe it has fin rot, ich, or some sort of infection. You may also notice it swimming to the bottom of the tank, perhaps trying to avoid some threat it perceives. 

Dull colors

Bettas are often known for their vibrant colors and beautiful fins. If you notice that your Betta’s coloration is a bit dull or it has developed stripes along its skin in a different color (stress stripes) then it may be under some form of stress. Stress stripes on females will often be more noticeable than in males.

Stress can also cause a form of depression in Bettas which can then cause their colors to become muted or dull. In rarer cases, the dull coloration can be due to a disease called “hole in the head” which is caused by an imbalance of bacteria in their system.

Watch out for skin or gill flukes or any white spots or specks or discoloration on your Betta’s skin as well. 

📚 Read More >> Why Do Betta Fish Lose Their Color?


Excessive hiding is another sign of stress from feeling unsafe, exposed, or threatened. Maybe your Betta’s tank mates are getting aggressive or there’s something outside the tank that your Betta perceives as a threat causing it to hide more. Check if there’s any fighting or signs of fighting such as fin nips and prevent any territorial disputes among your fish by providing enough hiding places (more plants or faux caves) or perhaps a bigger tank. Check the surroundings of your aquarium for anything that may be causing a reflection off the glass that looks like a threat to your Betta. 

Getting sick

If your Betta is suffering from an illness then this is a sign that it may be under stress. Stress often lowers one’s immune system making it harder to fight off illnesses. Aside from treating your Betta’s sickness, look into any environmental conditions that may be causing it stress and address these as well. 

Pro tip: Since a lot of stressors to fish come from their environment, make sure you have a good monitoring system in place and that all your instruments are accurate/up to date. Monthly cleaning of your tank and filters should be performed to help keep your tank’s water quality in good condition which will help keep your fish healthy. 

What Causes Stress In A Betta Fish?

Many factors can contribute to stress in Betta fish. The most common causes for stress include a tank that is too small, poor water conditions, fluctuating water temperatures, stress from tankmates, and illness.

Factors That Cause Low Stress In The Long Term

Factors that give your Betta fish low stress that can go on for a long time and eventually cause poor health conditions usually have something to do with inappropriate tank conditions. Though these may not cause immediate stress, the poor conditions can build up a feeling of stress that affects Bettas negatively in the long term.

Small tank size / a tank that is too small

Bettas should be in at least 5-gallon tanks and up. Anything smaller will make your Betta fish feel cramped and stress it out. Contrary to popular belief of a “30-second memory”, fish are actually cognitive and are quite intelligent. Your Betta can become quickly bored with the small tank space and lack of stimulation from the same surroundings. This can even cause depression. 

Smaller tanks also pollute quicker due to the smaller water volume which is another stressor that can lead to the poor health of your Betta. 

Improper tank conditions or water quality parameters

Water quality parameters such as pH, temperature, and pollutant concentrations (ammonium, nitrate, and nitrite) that are not the optimum levels for your fish’s tank can stress it out. The stress, along with the poor water quality can lower its immune systems and lead to illnesses. 

Regular water changes help prevent toxin buildup. If you use tap water in your tank, make sure you treat it for chlorine (water conditioners are readily available in pet stores).

Always make sure your tank equipment (heater, aerator, and filter) as well as your monitoring instruments (water test kit, thermometer) are in good working condition so you can keep your tank parameters top notch.


Bettas tend to be solitary fish so a tank that is overstocked and overcrowded will definitely stress them out. Different fish need different space and tank size needs though a general rule is a gallon per inch of fish length. Obviously, you’d want the biggest swimming space available for your fish and your Betta so always opt to stock your tank correctly according to its size. 

Even if your tank is big, if it is overcrowded or overstocked, your fish community can suffer from territory or space issues as well as water quality issues. Overstocked tanks have increased biological loads that your filter may not be able to keep up with. 

Lack of hiding places

Bettas are solitary and are sometimes reclusive so it’s important to have some decorations or furniture in your tank that can serve as hiding places. Plants and faux caves work, just make sure they do not have any sharp surfaces that can snag on the fins of your Betta. These areas can help your Betta feel safe especially when it feels a bit too exposed. This is still true even if your Betta has the tank all to himself, it can be stressed out in a bare tank with no places to hide. These decorations also serve to stimulate your Betta and give it places to explore.

Factors That Cause High Stress In The Short Term

Short-lived, high-stress conditions in Bettas often come from fights or sudden changes in water conditions. These can be short-lived but still affect their health negatively if left unchecked.

Sudden water quality changes

Abrupt water quality changes should always be avoided in tanks. Fish can sense these sudden changes and become stressed out. In the wild, they would be able to swim away from areas that have poor water quality but in tanks, this is not possible. So, keeping your water quality conditions stable is a must in aquarium keeping. 

Spikes in pH or water temperature, for example, can shock your Betta and stress it out. If it does not recover quickly from the trauma and shock, it can even die. Make sure your water parameters are well monitored to prevent this from happening and invest in high-quality, accurate instruments.

Sudden water quality changes can come from new additions to your tank. If you plan to introduce anything, make sure these are sterile and clean. A good way to acclimatize rocks or driftwood would be to soak them in water first for a week with an aerator to make sure any toxins leach out before adding them into your tank. Cleaning these materials properly also ensures that there are no parasites or bacteria that can end up in your tank. 

Sudden water quality spikes can also come from frequent water changes during cleaning. Try to lessen the amount of water you replace or perform less frequent partial water changes to help keep your parameters more stable.

📚 Read More >> How Long Will Fish Survive Without Power?


Even if Bettas are also known to be quite territorial, they can get bullied by other tank mates especially fin nippers. Since Bettas are not terribly fast swimmers, fin nippers can get to their fins, injuring them. These displays of aggression and fights can cause high, short-term stress. It can become long-term if left unaddressed. Injuries from fin nips can also develop into tail rot which can become a serious health condition. 

In the wild, these fights are avoided by fish by just swimming away to find another area that cannot be done in a tank. This is why it’s important to avoid overcrowding. Choose the correct tank size and provide ample hiding places to prevent territorial issues and aggression. 

Pro-tip: if you plan to keep a community tank, always look into species compatibility to make sure that the fish that you choose will not become aggressive towards each other. It’s also better to keep bigger tanks with lots of hiding places if you plan to keep different fish species with each other.


A health condition that is affecting your Betta such as a parasitic, bacterial, or fungal infection or fin rot can also cause it stress. Illnesses can affect your Betta’s appetite causing its immune system to further deteriorate. If left untreated, it can lead to a serious health condition, even death. It’s good to be familiar with common diseases affecting Bettas and their symptoms such as swim bladder disease, fin rot, ich, and constipation so you can spot these and treat them early.


How can I tell if my Betta is stressed?

Watch for any behavioral or visible signs of stress. Changes in behavior, erratic or darting swimming actions and excessive hiding are some signs. Lack of appetite and lethargy is also another possible sign of stress. Duller coloration on the skin or stripes on the skin also points to stress. 

What stresses Betta fish?

Stressors to fish in general, including Bettas, often come from their environment. Poor water quality, especially sudden changes in water parameters causes stress. Incorrect tank conditions (too small, too crowded, no hiding places) can also stress your Betta fish out. Aggressive tankmates are another stressor for Betta fish.

How can I calm my Betta fish down?

The best way to calm your Betta fish down will be to address the cause of stress. Check its tank conditions and make sure nothing is off especially in terms of water quality. Make sure there are no aggressive tank mates with your Betta and add a few more hiding places in the tank to help it feel safer. 

Can Bettas recover from stress?

Yes, Bettas can recover from stress especially if the cause is addressed immediately. However, long-term stress can cause irreversible damage to its immune system making your Betta sickly. Other diseases that may arise from prolonged stress can also become fatal. 

How can I tell if my Betta fish is happy?

If your Betta is not showing any of the symptoms and signs of stress then it is definitely happy. If it is swimming freely and eating comfortably, then it is happy. Another behavioral sign of a happy Betta fish is reproductive or breeding behavior. This means that it feels that the environmental conditions are right and safe enough for it to breed. Males build a bubble nest on the surface of the water indicating its readiness to mate.


If you have a well-kept tank with the optimum water and environmental conditions then you will have a stress-free Betta. Stressors to most fish often come from their environments and since they are in a closed system, small factors can escalate and cause a lot of stress that eventually affects their health. It’s usually easier to prevent potential stressors instead of addressing them as they come. Preventing stress is easy since you just have to keep good tank conditions for your Betta. 

Further reading

Overview articles on Bettas:
Siamese fighting fish
Betta Fish: The Beautiful, and Very Popular, Siamese Fighting Fish

Quick care sheet:
Betta Fish Care

US Fish Wildlife Service Summary on Betta Fish:
Betta splendens (Siamese Fighting Fish) Ecological Risk Screening Summary

Article about the proper care that Betta fish need as well as what stresses them out:
Betta fish often mistreated at pet stores and by owners,
Betta Fish: Facts and Why They’re Not ‘Starter Pets’