How To Euthanize A Fish (Humanely)

How To Euthanize A Fish (Humanely)


You have begun to notice that one of your saltwater fish are not doing well and have decided that it might be its time. You are making the decision to end this fish’s life early to save it from experiencing more pain than it deserves but you should first learn how to best euthanize a fish humanely and effectively.

There are actually a lot of methods for killing fish but only some of them are guaranteed to be humane while others might be or simply aren’t humane at all. If you care about your fish, you will want to follow the instruction below carefully to humanely euthanize your fish.

Additives For Euthanizing Or Healing Your Fish

Clove Oil

Add a few drops to some water and mix thoroughly. Add the mixture to a container with the fish. NOTE: Don’t add drops to the container with the fish. Mix first.

Baking Soda

Mix 1 tablespoon to 1 cup of water. Add the mixture to a container with the fish. NOTE: Don’t add baking soda to the container with the fish. Mix first.

Stress Guard

To prevent future illness or to help a sick fish, Stress Guard can help heal and boost the health of the fish in your aquarium.

Immune Support

Another great additive for boosting the health of your fish and corals. It’s also great for helping rehabilitate sick fish.

Should I remove dying fish from the tank?

If you’re certain that your fish is dying then you should definitely ready a container for them. You will want to follow one of the methods below for how best to deal with your fish.

However, you will want to understand what caused your fish to get to this point. If you are not sure, you will need to check the water quality and look for signs of trauma on the fish. Does your fish have stuff growing on it when it didn’t before? Are there scars or other bodily injuries? Depending on what has caused this trauma to your fish you will want to rectify the situation immediately, so more fish are not harmed by bad water quality, temperature spikes, or disease.

How to comfort a dying fish

As you prepare a space for your fish or prepare the necessary things you may need, you may want to try to keep your fish as comfortable as possible. You can try to keep loud noises to a minimum as fish are normally sensitive to noise but as they are already going through a traumatic experience limited other traumas will be beneficial. When you are finally ready to move your fish do it with as much care as you would if the fish was going to live another few years. Don’t shock it by throwing it into fresh ice cold tap water. You are trying to prepare a safe place for it to pass calmly after all.

When should you euthanize a fish?

There can be a few reasons why you might need to put your fish down like if you accidentally put the wrong water in the tank or if the fish was bullied by another fish. A fish can have a myriad of reasons why it might need to be put down, so it doesn’t have to suffer longer than it has to. What this means is that you should always look for changes in a fish’s eating behavior, swimming behavior, and color. Depending on the symptoms, you only have one option for your fish and that is to put it down as gently as you can.

How does a vet euthanize a fish?

Most likely, your vet will use an anesthetic overdose and usually done to larger fish but it is possible that your vet will opt for a different method depending on their preference and the type of fish.

You can definitely take your fish to be put down at a vet if it makes you squeamish or too sad to do it yourself but as we all know, it is expensive to go to the vet for anything. You will save more money in the long run if you learn to euthanize your fish quickly and humanely.

How to euthanize a fish with clove oil (preferred method)

This method is the most effective and the easiest and for squeamish people. It is also arguably the most humane way to euthanize your fish. The clove oil method to euthanize your fish only requires that you purchase a small bottle of clove oil. The only issue is clove only isn’t always readily available so depending on your circumstances you may need to look at the other methods listed below as backup plans. If you don’t have clove oil on hand baking soda is the next best choice. I do recommend picking up some clove oil now so you’ll have it on hand for the next time.

  • Remove your fish from the main display tank and place it in an appropriately sized bucket or bowl.
  • Create a water and clove oil solution. You can not add the oil directly into the bucket/bowl as it will not mix well which would mean you would need to stir the fish and that’s not creating a calm experience for your fish. Take a very small Tupperware container, fill it with water, and add a few drops of the clove oil. If you have a larger fish, you may need to increase the number of drops but use your common sense when creating the solution. Stir the solution together, if you have a lid to the container, put it on and shake a lot. The shaking will help to mix everything much faster.
  • Pour the clove oil solution into the water and wait for your fish to fall asleep. Once you notice that your fish is asleep, you will need to add more drops of clove oil to the water to finish euthanizing your fish. You should try adding 12 to finish it but watch for movement in the gills and fins to see if it might still be alive. After about 30 minutes, if you see the movement you should add more clove oil.

How to euthanize your fish with baking soda

You can also try a solution of 1 tablespoon of baking soda per cup of water and then adding your fish to the solution. It will take 15-20minutes for the fish to completely stop moving. This method is much more humane than vodka and more accessible than clove oil.

How to euthanize a fish with vodka

If you do not have clove oil on you and can’t find it in a reasonable amount of time, you might opt for vodka. I will be completely honest that I don’t think this method is that humane as it can hurt the fish before itis able to lose consciousness. The method requires that you take 1-part vodka and 4 parts water and place the fish in it. The fish will pass out and die from alcohol poisoning, but I recommend trying to find clove oil instead.

Potentially inhumane ways euthanize your fish

Blunt object or a knife

I personally could never do this to my fish but if you are comfortable and willing to follow through, you might opt for this method. Lay the fish down on a sheet of aluminum foil and cover it with more aluminum foil. You should use a blunt heavy object to strike its head as hard as you can. I warn you that this will only be humane if you don’t hesitate and you aim correctly. If you aren’t confident you can do that consider a different method.

You can also try to use a knife by slicing down the center of your fish’s skull. I recommend looking at this video (warning graphic) if you would like a better idea of how to do it. It is painless if done correctly but you need to know what you are doing.

Flushing your fish

There is no guarantee that flushing your fish will kill it. All you are really doing to your fish is sending it to a different place to die. You are removing the responsibility from yourself. It will die a slow death in sewers or even at the water treatment plant, so it is best to avoid this method of “killing.” 

Carbon Dioxide

Sure you can inject carbon dioxide into the tank to kill your fish but it won’t help to kill the fish in a humane way. Like flushing down the toilet, this method is done when you don’t really care about your fish as the fish isn’t lulled into unconsciousness but is instead gasping for air until they pass. You may as well remove the water altogether.

Note: don’t suffocate your fish to euthanize.

What to do with unwanted aquarium fish

If your fish is not dying but you simply don’t want it anymore, you should be trying to find it a new home rather than killing it. You can try to contact a local pet store to see if they will buy it off of you but what could be even better would be if you know a fellow aquarist who might like that specific fish. You can reach out to other locals in your area who might have saltwater tanks and see if they might like free fish. Like any other pet, you should be doing your best to find your fish a new home since you took the initial responsibility of caring for it. If you read this article only to find a way to dispose of a fish you do not want, I hope you strongly consider relocating your fish to a new home that will take proper care of it. Fish are just like cats or dogs as they trust you to care for them to the best of your ability and you accept that responsibility when you take on the hobby.

Final thoughts

Hopefully, now you have a better understanding of how best to care for your fish that may be dying. Your fish is a part of your family and you should help to put it to rest as humanely as you possibly can. if you plan on keeping fish for a long time, you should plan to put some down at some point in your time being an aquarist so you should plan to keep clove oil or baking soda on you at all times for just these moments. It will help to lessen the stress on you as you take on your final responsibility to your fish.

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