How to Euthanize a Fish

An aquarium fish can be euthanized either by putting your fish in the freezer, a cup ice water, or by putting the fish into high proof rubbing alcohol.

When to Euthanize a Fish

It’s never an easy decision to euthanize fish. However if your fish has been suffering and shows no signs of recovery, it may be the right decision, regardless of how difficult it can be.
When you are forced to euthanize a fish, it’s important that their death be humane as possible. The goal is to minimize pain and suffering. They have been your pet and you owe them at least that much.

The Freezer Method for Euthanizing a Fish

The freezer method is a painless, but slow, method of euthanizing a fish. Remember, fish are cold blooded. This means they rely on their exterior environment to maintain their body temperature. When the water they live in gets cold, their body temperature starts to cool. As the water cools, the fish become less and less active. Eventually, some of their internal systems start shutting down. Ultimately, their whole body shuts down and they pass away peacefully and painlessly.
The freezer method relies on using your freezer to slowly lower the body temperature.

What You’ll Need

• A solo cup/An old tupperware/Something disposable and small, but large enough that your fish will fit
• A freezer
• Cling-wrap

The old tupperware can also be a bowl, small bucket, or any other vessel that’s large enough to hold a fish. You’re going to throw this out after the deed is done. So don’t use anything new or valuable to you.

The Steps

1. Fill your container about ¾ of the way up with aquarium water. Don’t use tap water as this will cause some discomfort for your fish.
2. Using your net, scoop out the fish and put it in the container.
3. Put cling wrap over the container. This serves two purposes. First it will ensure that your fish does not jump out into your freezer. Second, it helps keep any nasties (bacteria, germs, etc) contained in the tupperware and not in your freezer.
4. Say a few words. A prayer. Throw a small ceremony. Whatever.
5. Put the container with your fish in you freezer.
6. 10-12 hours later, remove the container and dispose of the fish.

Using Ice Water to Euthanize a Fish

The ice water method uses water filled with ice to shock your fish and kill them almost instantly.

What You’ll Need

• A solo cup/An old tupperware/Something disposable and small, but large enough that your fish will fit
• Ice
• Water
• Cling Wrap

The Steps

1. Fill your vessel with water and ice.
2. Scoop your fish out of the aquarium.
3. Put your fish in the ice water
4. Your fish will stop moving within 5-10 seconds
5. Cover the container with cling wrap.
6. Put the container in the freezer for several hours until the water has frozen solid
7. Dispose of the fish.

Using Alcohol to Euthanize a Fish

The alcohol method uses high proof alcohol to quickly numb and then kill the fish.

What You’ll Need

• A solo cup/An old tupperware/Something disposable and small, but large enough that your fish will fit
• High proof alcohol – Rubbing alcohol, grain alcohol, vodka, tequila, rum, any other spirit that’s at least 70 proof

The Steps

1. Fill your vessel with the alcohol.
2. Scoop your fish out of the aquarium.
3. Put your fish in the alcohol
4. Your fish will stop moving within 30 seconds.
5. Leave your fish in for 5 minutes, just to be sure.
6. Dispose of the fish.