How To Euthanize A Betta Fish (The Most Humane Ways)

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Within a short time, pets become a part of the family, and when it’s time, goodbyes are seldom easy.  

While some live a long, fulfilling life, others don’t share that fortune. Fishes come in the latter category, and you will often find that they get sick or pass on quickly. If you have a betta fish who has not been keeping well at home or in the office, it may be time to let go.

But euthanizing a pet is not easy and needs to be done humanely and respectfully. Read on below for more information on how to euthanize a betta fish.

When To Euthanize A Betta Fish?

Fatal Diseases in Bettas

Fish Tuberculosis 

Fish tuberculosis is caused by the Mycobacterium spp. There are over 150 Mycobacterium species, some of which can be found in soil and water. As one of the common environmental contaminants, they do not require a fish host to survive.

While Fish Tuberculosis is not as prevalent as it used to be, it is still possible for fish to get TB and spread it to humans through open wounds. You will know that the fish has contracted TB through signs like loss of scales, discoloration in the body, and skeletal deformities. 

A Betta fish suffering from fish Tb is not treatable, and the only option for treatment would be euthanasia. If a betta shows signs of this deadly disease, it should immediately be isolated to prevent any spread of infection.


Columnaris is a potentially fatal bacterial infection that presents itself in the form of mold-like lesion. This is one of the common bacterial infections that Betta contract due to poor water quality, stress, or an inadequate diet. 

The name for Columnaris is derived from the bacteria’s columnar-shaped appearance, which can be found in virtually all aquarium environments. It has also been referred to as the cotton wool disease, saddleback disease, or guppy disease.

The biggest issue with this disease is that it can occur slowly or spread quickly, killing the Betta fish in just a few hours. So it is essential to keep a lookout for signs that might allow you to do something about it, such as:

  • Grayish spots on the mouth, edges of scales, or fins 
  • Lesions on the back and the sides
  • The disintegration of fins and gills
  • A layer of moldy or cottony lesions grows around the mouth

The course of the disease is sped up by high water temperature. However, lowering it will not slow down or affect its progression. The Columnaris bacteria (F. columnare) can be treated with antibiotics and prevented via basic tank maintenance.


A pinecone-like Appearance

Dropsy is not an independent disease but more like a sign to show that the fish might be suffering from other issues like TB or a tumor. If you notice that your fish has a bit of swelling in the abdomen or the scales are sticking out, then they may be suffering from dropsy. 

In most cases, both physical and behavioral symptoms are observed.

  • A pinecone-like appearance
  • Visual bloat and swelling of the belly
  • Eyes are popping out
  • Color loss
  • Clamped fins
  • Extreme lethargy
  • Stop eating 
  • Swimming near the top of the tank.

Dropsy can come from multiple factors that weaken your Betta fish’s immune system. The gram-negative Aeromonas bacteria are considered the main cause, which will only lead to serious infection for fish that already have an impaired immune system. 

Dropsy is extremely difficult to treat; by the time your Betta has a pine cone appearance, severe internal damage has already occurred.

Betta Fish Behaviour Before Death

Betta fish have tell-tale signs that can indicate they are closer to their demise. If you are a first-time fish owner, it is essential to keep these signs in mind.

Poor Appetite 

This is one of the first signs to look out for, not just in terms of death but general sickness. If your fish seems disinterested in food during normal feeding time, consider it a red flag. Betta fishes have a decent appetite, so not eating or spitting the food out clearly indicates that something is wrong. 

In some cases, the betta fish might come up to the surface but not eat. That is a sign of it gasping for air which could also indicate that they may be suffering. 


Betta fishes are known for their color. Discoloration in their skin or even a slight fade indicates poor health conditions. 

A fatal fish illness that many beginners face is nitrite poisoning. When the levels of nitrites spike, you will notice your little guy has a red belly which means it needs emergency veterinarian care and probably euthanization.

However, some color fading is normal and should be expected. Colour fade in marbling Bettas are part of the aging process, but it can also indicate a health problem if your Betta’s body suddenly loses all its color or develops signs such as pale gills, which may cause you to worry about them.

Also, remember, the older the fish gets, the more its skin will fade. It does not always have to be a fatal disease; it could just be old age too.

Lack Of Response 

Any healthy fish, Betta or otherwise, will respond promptly and eagerly. But if a betta is non-responsive, isolated, and seems tired, there is a chance it might be unwell. 

A sick Betta fish typically becomes less responsive to gestures and movements. It would rather sleep or isolate itself from its owner’s presence, as it is in a weakened state of health.

If you are concerned whether your Betta is lethargic or just sleeping, try offering them food and turning on the lights to see if they wake up.

How To Humanely Euthanize A Fish

Putting a pet down is never easy, but that does not mean it has to be done in an inhumane way. There are two main ways of getting the job done in a way that ensures your fish is let go with love and respect.

Clove Oil 

Clove oil is readily found and has the properties to make a small fish unconscious. When mixed with warm water, it can be added to the tank in small doses. The first dose will render the fish unconscious, while the second will allow it to pass away in its sleep. 

Observe the fish carefully in this solution, ensuring they are fully submerged, and their gills aren’t moving. The concentration of the solution should be appropriate for your size of fish; if it’s too small or large, you run a high risk of killing them by accident. Once all sign of life is gone from their gills (i.e., there isn’t any movement) after 10 minutes, then place them into the freezer to make double sure that they’re dead before disposal!

TMS Buffered with Baking Soda

This is the professional anesthetic that labs and aquariums use for sedation, euthanasia, or anesthesia, which has been proved for euthanizing laboratory fish softly.

Add the most common agent, TMS (also known as MS-222), slowly until the gills stop moving. To ensure that the fish has died, add a shot of grain alcohol after about 10 minutes. 

Anesthetics like MS-222 are not readily available but can be procured after consultation with a vet.

Author note: Fish must be held 21 days before release if anesthetized with MS-222.

How To NOT Kill Your Betta Fish

The methods mentioned below will most likely kill your fish brutally, so we recommend steering clear of these.


Aka, fish poison. It is like giving chocolate to a dog or any form of poison to anyone suffering. Many people recommend vodkaand it might do the job, but it’s not a nice way to go.


This is an easy way to get rid of a fish but not the right one. Especially since certain fishes tend to survive, and flushing them is just torture. 

Ice Water 

Placing the fish in ice water may be suitable for some fish but not betta fishes. The ice formation on the gills, if they have a chance to survive, is painful and can kill them.


Can You Euthanize A Betta With Melafix (Tea Tree Oil)?

There have been varied opinions on this as tons of people have treated tanks with Melafix. However, considering it is an oil, much like clove oil, there is a chance it can euthanize bettas. We still recommend using clove oil or Pimafix for this.

Is It Okay To Flush A Dead Fish Down The Toilet?

Flushing a fish is never an option for two main reasons. Firstly, the toilet tank or drain is not meant to handle foreign objects. And secondly, it is an inhumane way to let your pet go, especially if the death has not been verified. 

Final Thoughts

With that, we come to the end of this guide on euthanizing a betta fish.

Remember to verify the death of your fish before taking the next step and burying it. It is advisable to give the fish at least 30 minutes to check for gill movement. If there is no movement or eye rolls even after that time, the fish has passed on. 

On that note, we shall sign off. We know dealing with moments like this can be challenging, but using the methods recommended above will ensure that you let go of your pets in the most humane way.

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Jeff Colt

Jeff Colt

Hello, I'm Jeff- an aquarium enthusiast with over 25 years of experience caring for a wide array of tropical fish, including koi, goldfish bettas, cichlids and more! For me: Aquariums are like jello - there's always room for more!

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