How to Euthanize a Fish humanely and safe

Nothing is as heartbreaking as losing your fish, especially if it has been with you for quite a long time. You did everything you could do to make it healthy. However, the methods you did were not working, and your fish is now struggling to live.

Many aquarists do not realize that it is possible to euthanize a fish. This might be your only option if it is slowly dying and in pain.

Some people do not want to do it, as this method can make them guilty. Instead, they prefer to let nature do its own thing and let the fish die on its own.

You can choose between these two options – it’s either you can let things go on their own or euthanize your fish to speed things up.

If you want the latter, then read this guide to know how to euthanize a fish humanely. Otherwise, you can leave your fish to die naturally but face the consequences of letting it suffer before it dies.

Short Answer

There are many ways to euthanize the fish if you want to speed things up. Some of the most humane methods are killing the fish using clove oil, anesthetic overdose, and stabbing it with a knife.

Moreover, these methods are easy to follow. It will depend on what way you prefer to euthanize your fish.

Long Answer

Euthanizing a fish can be heartbreaking for many people. However, it is the ideal option, especially if they no longer want to see their fish suffering. If you’re one of these people who wish to settle things with your fish for good, then euthanize it.

There are many humane ways you can kill a fish. This includes killing it with clove oil, an anesthetic overdose, and a knife.

However, you might want to avoid going for inhumane methods such as using vodka, boiling water, ice bath, suffocation, carbon dioxide, and flushing the fish down the toilet. In this way, you’ll avoid seeing your fish suffer from the inhumane method of killing.

When and Why Do I need to kill my beloved Fish?

An aquarium is a dangerous place for fishes, especially if they are not entirely suited to the environmental conditions.

If you own fishes in your aquarium, one species can attack or injure the other. This leaves the battered fish sick and injured. Because of this, recovery is almost impossible. Therefore, it’s better to kill it for good.

Another reason for killing your fish is when pests like hydra, columnaris, or freshwater itch can hurt it. These pests will gradually cause sickness to your fish.

Furthermore, if you recently added untreated tap water to your aquarium, the pH change can affect the fish’ survival in the water tank.

Unfortunately, it is entirely impossible to revive your fish successfully. Once it gets sick and does not recover for a while, killing it will be the best option.

Methods to kill a Pet Fish humanely

When it comes to euthanizing your beloved fish humanely, there many options to choose from.

These methods are recommended for you not to feel so much guilt when killing your fish. Moreover, they are simple to follow. Read more to know about the different methods.


1st Method: A Clove Oil Bath


The first method of euthanizing the fish is through the clove oil bath method. This procedure is popular since it is the least violent way to kill your fish.

Bathing your fish with clove oil is effective and least violent since it works as anesthetics, causing your fish to breathe slower until it dies. Think of this method as like putting your fish to sleep until it does not breathe anymore.

Using this method will not violently kill your fish, as the gills won’t burn. You also don’t need precision to euthanize it.

For the process, you need the following materials:

  • Clove essential oil or pure clove oil – This type of oil can be found in pharmacies, health shops, and other supermarkets.
  • Large bowl or container where a fish can fit in – It must have an amount of space where the fish can still move around and not feel cramped.
  • Another small container to mix the clove oil
  • Optional: Air pump


  1. First, fill the large container or bowl with de-chlorinated or tap water from the fish tank.
  2. Place a half-full of water into the smaller container. Then, pour 3 to 4 drops of clove oil into it. Mix the oil with the water by shaking it.
  3. Turn on the air pump from the tank and place it in the large bowl.
  4. Pour the mixture from the small container to the large one evenly. However, if you don’t have an air pump, stir or shake the mixture until the water becomes colored.
  5. Carefully place your fish into the large container together with the mixture. Observe your fish and wait until it breathes slowly and falls to the bottom.
  6. Add 5 to 7 drops of clove oil, then emulsify it with the mixture. Wait until the fish does not move any longer for at least 5 minutes.
  7. Lastly, throw your fish.


2nd Method: Anaesthetic Overdose

Another safe and humane way to euthanize your fish is by overdosing it with anesthetics. This method is most appropriate for large fish. However, a veterinarian should carry out this procedure as some anesthetics are not available over the counter.

The veterinarian knows the best way to euthanize different species of fish. Besides, some species react in different ways to certain anesthetics. Depending on the fish species and how it reacts to the drugs, the veterinarian might use another method to kill it for good.

If you want to do it your own, you can buy Tricaine Methanesulfonate (TMS), which you can purchase from a pet supply store. You have to pour twice the recommended dosage into the fish tank to euthanize the fish thoroughly.

This substance is FDA approved as it is the only product that the FDA only recognizes as the best method of killing a fish.

On the other hand, if you want to leave it to a veterinarian’s hands, a drug such as Benzocaine Hydrochloride is usually used.

This product is not sold over the counter or in shops. As long as the drug is mixed with water, it will not irritate the fish tissue. Also, the fish will not struggle before it dies.


3rd Method: Physical Euthanization with a Knife

The last humane method of killing a fish is by using a knife. This method is pretty self-explanatory.

Remove the fish from the tank, then use the knife to chop its head. The fish might feel a momentary pain when you slice off its head. However, it is the quickest and easiest way to kill it without having to suffer longer.

Another method for killing a fish is to target the brain directly. To accurately hit the fish’s brain, pierce the eyes horizontally with a knife and push it through. You’ll know it is dead if it stops moving.

Which Methods should I not use because of Inhumanity?

As mentioned above, there are humane and inhumane ways to euthanize a fish. Since the humane methods have been discussed, now is the time to explore ones you should avoid.

The inhumane methods include using vodka or baking soda, dipping the fish into boiling water and ice water, suffocate it, and flushing it down the toilet. These methods are not recommended to use. Hence, avoid them at all costs.

Moreover, these are the reason why these methods should be avoided:


Using Vodka

Using vodka certainly works for killing a fish. This method looks pretty much similar to using clove oil. However, alcohol can cause the fish gills to burn, causing the fish to die in excruciating pain. Of course, it depends on how much vodka you’ll be using.

There are usually two methods when using vodka. First, place the fish into a large container with a 10% alcohol solution (1 part vodka and four parts of water). With alcohol, the fish becomes intoxicated, which leads to death.

The second method is to submerge the fish into a large container with mostly 95% vodka or pure alcohol. The solution will cause immediate pain and shock to the fish, causing it to die instantly.

Either method will kill your fish for sure. It does not matter which is less painful because both do not promote humane killing.

The first one might sound good since it will only put the fish to sleep until it dies. However, death will be a long process for the fish, as it will feel excruciating pain since the gills are likely burned.

The second method might sound harsh, but it can kill the fish instantly. In this way, it won’t suffer from pain due to shock.

Both would effectively work, but one is not better than the other. Besides, submerging the fish into an alcohol solution is one of the cruel ways to kill a fish, no matter the amount of solution you use.


Boiling Water

Dumping the fish into boiling water is another method for killing a fish. The reason why it is not suggested is that it can cause distress to the fish.

If the boiling water is too high, it can instantly kill the fish. Otherwise, the fish might feel pain before completely dying if the boiling water is not high enough. This procedure is not useful for large fish, albeit it works for smaller ones.


Using an Ice Bath

Just like boiling water, freezing water can induce loss of consciousness in the fish. It may also inflict distress before it dies.

When using this method, be sure that the ice water must be cold as possible. Then, dump the fish into the cold water, and it will instantly shock to death.

Submerging the fish into an ice bath might be effective, but it can inflict pain to the fish before it dies. Thus, you should never do it to kill a fish if you don’t want it to suffer before it dies.



If you try to suffocate the fish by leaving it on dry land, it will surely die. However, killing this way is not a quick process.

The fish’ organs will start to fail slowly, leading to its suffering. This method is painful and probably some of the most horrible ways to kill it. Remember, your fish deserves a painless death.


Carbon Dioxide (e.g., Baking Soda)

Adding baking soda to the water creates carbon dioxide to the water, which intoxicates a fish. This method might sound painless for the fish’s part. However, your fish might thrash around for a bit before dying, like how it moves when it is out of water.

Your fish will mostly struggle before dying, especially if you do this method wrong. Also, you won’t entirely kill it in an instant. You might still need to freeze or decapitate your fish to make sure it is dead.


Flushing Down the Toilet

Avoid flushing the fish down the toilet. You should flush it only when it’s dead, not when it’s still alive.

The reason is, flushing will not kill the fish quickly. When you flush it, it will get shocked by the temperature and the surrounding chemicals when it travels through a pipe. It can also experience scraping and bumping until it arrives into the pool of human waste.

Once it lands there, it will suffer from burning and might be attacked by parasites, which causes it to suffer before dying. If you want to kill your fish quickly, you should never do this. You might probably choose to let the fish die in a tank on its own rather than flushing it.

How can I verify the Death of my Fish?

Whatever humane method you use for killing a fish, you must ensure that it is dead before you throw it.

There are ways you can check it. Here are the following:

  1. If you used the clove oil and overdose of anesthetic for killing the fish, observe the fish. If you find it either on top of the container or at the bottom, it is dead.

You also need to check for signs of movement from its gills. When it’s not moving anymore, your fish is gone for good.

  1. Another way is to touch your fish gently. Make sure to use a net to scoop out the fish. If it moves away, it’s still alive. Otherwise, it’s dead. Then, scoop it out to throw it away.
  2. Check the eyes. The eyes must be sunken into its head and gray-colored to confirm it is dead.
  3. Lastly, if you have stabbed the fish, it will stop moving when it is dead. Wait after 30 minutes to ensure it is completely dead before you dispose of it.

Conclusion – How to Euthanize a Fish

Euthanizing your beloved fish is not an easy decision. However, when it’s sick because another fish has attacked it or disagrees with the water’s pH, you probably need to take this route. Besides, as owners, we should act according to our fish’s best interest, even if it means ending its life.

Fortunately, there are humane ways to kill your beloved pet. Submerging your fish into a mixture of clove oil or drug in a large container will kill it less painfully.

Also, decapitating it by piercing through the eyes or by its head will kill it instantly. These methods are acceptable since the fish would not have to struggle in pain before it dies.

Moreover, there are other ways you can kill it, but these are not suggested since the fish will feel pain before it dies. These methods, termed as inhumane, are the following – submerging it with vodka, boiling and ice water, baking soda, suffocating and flushing it down the toilet.

Do not use these methods if you don’t want to cause pain to your fish. Besides, it’s way better to leave your fish to die by itself in the tank rather than following these techniques.

Since you have decided to euthanize your fish, follow one of the humane ways and choose the easiest one for you.

After all, we want our fish to die in the most painless way possible. Prolonging its condition will only add to its suffering, which we don’t want to happen.

Lastly, make sure to check for signs of life before throwing it away. The eyes should be sunken and grayish, with no signs of movement, and floats either on top or bottom of the container. It should not also move upon touching it.

Once you see these lifeless signs from your fish, then it’s time to say goodbye.

We hope our guide has provided you ways on how to euthanize your fish humanely. Euthanizing means farewell to your beloved fish.

However, you can buy a new one to entertain you next time. Just make sure to take care of it properly to have a long and healthy life.

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