How to Euthanize Guppy Fish the Most Humane Way?

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Putting your pet down is never an easy decision. It’s a soul crushing thing, but sometimes it’s the only way to end its needless suffering.

When it comes to euthanizing guppy fish, there are various methods that aquarists use, although not all methods are humane.

If you ever find yourself in a situation when your guppies are so sick and suffering that prolonging their life is in of itself cruel, this article can serve as a guide on how to euthanize guppy fish in a humane way.

I’m going to cover the most humane way to euthanize your guppy fish and some of the methods that should not be used to end the life of your fish.

Why Do You Need to Euthanize Your Fish?

As an aquarist you’ve taken it upon yourself to offer your fish the best care possible. But if you’re just starting out in the field, you may lack the experience needed to pull this off.

You may not be experienced enough to spot diseases or prevent injuries in the tank, both of which can leave your fish in a seriously bad condition.

You may also not know how to properly cycle your tank; you may accidentally introduce diseases into the aquarium by adding infected fish or live foods that carry diseases.

But even with the best care possible, things can go south and there may come a time when you must consider putting down your beloved fish.

When the disease or injury is so serious that there is no hope for recovery and your fish will suffer days on end, dying eventually, killing them to end their suffering is actually the merciful thing to do.

If you can’t stomach putting your fish out of misery yourself, you can ask a veterinarian to do it for you.

This will make your wallet a bit lighter though, so maybe it’s a good skill to have in case you are short on cash or can’t get to a vet in a reasonable amount of time.

Therefore, in case of fatal diseases such as fish TB, advanced bent spine syndrome, or brutal injuries, euthanasia will ensure that your fish will no longer have to needlessly suffer.

Of course, the idea is to inflict the least amount of suffering, which is why methods that are only putting your fish through further pain should not be used.

But first, let’s examine the most humane ways to end the life of your beloved guppy fish.

How to Humanely Kill Your Guppy Fish?

Just to be clear, euthanasia should only be used as a last resort option if all other treatment options have been exhausted and there is no option left but to end the suffering of your fish.

It should not be used to dispose of otherwise healthy fish or unwanted pets. If you are unable to keep your fish any longer, sell them, let somebody else have them for free, etc.

When looking for a humane way to kill a pet fish, there are two methods that I would consider humane — one is quick, although a bit gore for the faint of heart, the other is slower, but more suited for those who can’t stand the more gory stuff.

The Clove Oil Method

This method is approved by the American Veterinary Medical Association as a gentle and humane way to put down your fish.

Clove oil has the effects of anesthetics used by vets, and it’s widely available. You can order clove oil off Amazon just to have a bottle around should it ever come to it.

For this method you’ll need:

  • A bucket or container;
  • Clove oil;
  • Small mixture bowl or pill container;
  • Protective equipment (especially if your fish have a disease that humans can contract too, e.g. fish TB).

Here’s a step-by-step on how to use clove oil to kill terminally ill fish:

Step 1: Fill the bucket or container with aquarium water

A gallon of water is enough, although bigger fish may require a larger container with more water.

Step 2: Catch the fish and place it into the bucket

Be gentle, don’t stress out your fish when moving it into the bucket.

Step 3: Mix clove oil with a bit of water

Don’t add the clove oil directly to the bucket of water because the oil won’t mix with the water and just ends up floating on the surface.

Instead put 4 drops (add a few drops more if you have fish larger than 4 inches) of clove oil into the small container, add water, place a lit on it and give it a good shake to mix it up.

Step 4: Add the mixture to the water in your bucket

Take the mixture and slowly add it to the water gently stirring with your hand. In a few minutes you should notice your fish stop moving.

It’s not dead yet, it simply lost consciousness (you’ll still see its gills moving). If after 5 minutes, your fish is still active in the bucket, add some more drops into the water.

Step 5: Add a stronger dose of clove mixture

Now that your fish is unconscious, add a mixture of 12 drops of clove oil. This will induce hypoxia and kill your fish. If the gills stop moving for about 10 minutes, it means you’ve successfully euthanized your fish.

The Stun and Stab Method

I must admit that this method is somewhat violent, but if done correctly, it’s quick and painless. As its name suggests, it’s 2-stage process that requires a blunt object and a knife.

You’ll also need an aluminum foil, a rolling pin, and a sharp knife.

You can even sedate the fish first with clove oil, especially if it’s larger and the clove oil mixture hasn’t induced hypoxia.

Step 1: Place fish on aluminum foil

Quickly take out the fish from the tank place it in the center of an aluminum foil square and fold over the square to prevent blood and whatnot flying around.

Step 2: Aim for the head of the fish with the rolling pin

Hit the head of the fish with the blunt object as hard as you can to disable its nervous system, so it doesn’t feel anything. If you have a smaller fish, this will outright kill it. If not, proceed to step 3.

Step 3: Stab your fish

This method of stabbing your fish is called pithing and the idea is to pierce it through the brain, which is located just behind the eyes. Pierce horizontally just above the eyes.

This will kill it instantly and it won’t feel anything since it’s already knocked out from the hitting.

I know this isn’t a method doesn’t sound that sound humane, but it’s effective and quick if done correctly. If you’re not sure you can pull this off, I recommend sticking with the clove oil method.

How NOT to Kill Your Guppy Fish

So far, these two methods are the most humane. A grey area method that may work for some fish, but not for others is immersing your fish in ice water.

For fish that can survive at colder temperatures too (e.g. goldfish), it may not be a humane way to dispose of them, but it can be a humane way to kill Zebra Danio fish, for example.

Because you can’t be absolutely sure on its effects on other fish, I say we add this to the list of inhumane ways to kill your fish along with the following methods:

  • Flushing your fish down the toilet (it’s inhumane because 1) it won’t die instantly and it may take a couple of days or even weeks; and 2) goldfish have been reported to survive it, which means you won’t end up killing it sooner than it would have died in your aquarium);
  • Injecting carbon dioxide into the water (yes, this will kill your fish but not in a short amount of time, causing them needless suffering);
  • Letting them suffocate outside of the aquarium (this too is a lengthier process that will only induce further suffering, so don’t do it);
  • Using an alcohol bath to kill your fish (while alcohol will kill your fish, it will also burn their gills and it’s not a nice way to go);
  • Placing your fish in boiling water (this is a horrible way to end the suffering of your fish, so don’t do it).

Although some of these methods may seem less violent than the stun and stab method, they’re more suffering-inducing than the stun and stab.

The key is to quickly end their life with the least amount of pain possible and the two humane methods I described above do just that.


I hope you never have to euthanize your fish and they’ll all die of old age instead. But if it comes to it and the vet isn’t an option for you — either financially or otherwise — I hope you’ll use the humane methods of euthanasia I described in this article.

Updated: July 31, 2022
Questions & Answers
  1. Thank you! My male guppy (Sunny) is on year 3 and has been slowly deteriorating. He spends his days lately breathing heavily at the bottom of the tank on his side or belly up. He can swim, but not in the direction he chooses and it almost seems like parts of his body are paralyzed. Today parts of his body are paler than normal. I’ve been feeding him his food via a turkey baster so I can spot feed him since he cannot swim accurately enough to catch the food. He seems grateful for my effort as he voraciously gobbles up the food. The two Diamond Tetras (Glimmer and Sparkle) hover about him sometimes and I wonder if they miss their mischievous pal who would spend hours chasing them about the tank. I realized today he’s not getting any better and someday he probably wont want to eat anymore either. When that time comes I’m thankful for your advice on clove oil and if he doesn’t pass in the night I’ll see if I can summon the courage to ease his suffering with that method.

    1. avatar

      Hey Sam! Unfortunately guppies do not live for very long time. 3 years is indeed a very old age in guppies. When guppies start swimming on their side or upside down, it is a sign of swim bladder disorder, which can not be treated. Sure, you can stop the suffering by using the euthanize method I described above. In this case it is recommended.

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