Content

• To step
• Method 1 of 3: Preparing an aquarium fish for euthanasia
• Method 2 of 3: Preparing for a euthanasia bath
• Method 3 of 3: Physical killing
• Tips
• Warnings

If you have a seriously ill aquarium fish, it is more humane to put it out of its misery. A freshly caught fish will inevitably feel some pain, but there are ways to minimize this and kill it quickly.

To step

Method 1 of 3: Preparing an aquarium fish for euthanasia

1. Ask a vet if possible. There are many different types of aquarium fish and for most it is unknown what the ideal dosage of drugs is. A vet is trained to recognize the signs of pain and adjust the process if necessary, so that he can give your fish a less painful death.
   • This article only lists methods that can reasonably be performed at home. Other methods, such as electrocution and lethal injection, are difficult to perform humanely without qualification, and / or can be harmful to the person performing them.
2. Find out what kind of fish you have. An ice bath or some medicine can be humane for one fish species, but painful for another. The instructions below give you the information you need to avoid mistakes where possible. However, an online search for information about euthanasia for your specific fish species provides more concrete recommendations. Most fish species have not been studied, but a few minutes is still worth it in case yours is.
3. Keep the fish in a quiet area. Keep the fish in a quiet room. Block light with an opaque aquarium lid or use red light that barely penetrates the water. These measures reduce the amount of light stimulation the fish receives, but provide enough light for you to work.
4. Do not feed your fish 24-48 hours before the euthanasia is administered. Wait that long before feeding the fish, unless the fish is almost dead. The fish absorbs the killer more quickly on an empty stomach and is less likely to break it out.
   • Skip this step if you are using a non-drug method.
5. Continue with one of the methods below. All methods listed below are humane ways to euthanize a fish. Read the instructions carefully before you start. Not all methods are suitable for all types. A euthanasia bath is not suitable for fish that you want to eat.

Method 2 of 3: Preparing for a euthanasia bath

1. Prepare a separate aquarium. Unless all the fish in the tank need to be killed, you will need a second container. Transfer some water from the current aquarium to a new, clean container that preferably has a similar air filter and temperature system. Using water from a different source or at a different temperature can stress the fish or cause inhumane death.
   • Some medications, including MS-222, may not be effective in temperatures below 10ºC.
   • Euthanizing a large aquarium full of fish is difficult and requires oxygen and chemical concentration measurements to calculate the best dose. Ask a vet to perform this if possible.
2. Consider using benzocaine or 2-phenoxy. These substances are both suitable for both fresh and saltwater fish and available at pharmacies without a prescription. The usual injection fluids for euthanasia such as T-61 and Pentobarbital-Ma may only be used by veterinarians and other substances such as tricain sulphate (MS-222) and Metomidate (Hypnodil) are no longer available to veterinarians. Caution: Benzocaine can cause a hypersensitivity reaction in contact with the skin. Dosage: dissolve 5 grams of benzocaine in 25 ml of acetone. The pharmacist can also do this for you. Add 2 ml of this solution to 1 liter of aquarium water in a container and add the fish (es) to be killed. Within minutes the fish are dead.
   • Do not eat fish killed in this way.
3. Do not consume alcohol. Many people will tell you that alcohol is a painless way to euthanize your fish. This is incorrect. It results in burnt gills and is very painful for fish.
   • Using alcohol to euthanize fish has been compared to dipping a person in gasoline to euthanize them. Do not do it!
4. Be careful with clove oil. It is not easy to say how concentrated a bottle of clove oil is or what it even contains. It can put your fish to sleep, but it doesn't have to kill them. The fish are not safe to eat and the water can be harmful if it enters the water supply. If you decide to use it, use this method:
   • Put a drop in some water until it is milky and then add it to the aquarium.
   • When the fish has fallen asleep on the bottom, add another 13 drops per liter of water.
5. Transfer the fish. Once you have administered your chosen medication, catch the fish and quickly transfer them to the euthanasia bath. Touch them as little as possible to avoid stress.
6. Wait for the fish to die. If too little of the euthanasia is used, the fish will only fall asleep. Death often doesn't occur until after 30 minutes, and you may have to wait 2 hours to be sure. Pay close attention to the following signs of death:
   • No movement or movement of the gills for 10 minutes. (often followed by spasms one minute apart).
   • No movement of the eyes when the fish is rocked up and down.
   • Very slow heartbeat. The heart may continue to beat after death, but a strong, sustained heartbeat means the fish is alive.
   • If you don't see these signs within an hour or two, or if the fish wakes up again, add more of the drug.
   • If you want to make sure the fish is dead, kill it using the physical methods below or freeze it in ice water. This shouldn't hurt if the fish is heavily sedated.

Method 3 of 3: Physical killing

1. Think about your equity and response. These methods are only humane if you can perform them accurately and quickly. Skip a section if you think the image of slime or a struggling fish is too much for you. These methods are often used to kill fish for food or research, not pets.
   • Practice on dead fish first so that you can perform these methods quickly and without errors unless you are experienced with fish anatomy.
2. Shred small fish. Fish smaller than 2 cm can be killed instantly in a fish shredder that shreds them with fast spinning blades. Make sure to use a shredder suitable for the size of your fish.
   • The bigger the fish, the less humane it is dead. Even if you have a shredder for bigger fish it can be painful.
3. Knock the fish unconscious (optional). Paralyze the fish by hitting it just above the eyes with a large enough hard object. Repeat with more force if the fish is still conscious. There is evidence that some fish species can remain conscious after decapitation, so this step is highly recommended.
   • Fish species that have adapted to a low oxygen environment are more likely to remain conscious after decapitation.
4. Decapitate the fish. Hold the head and cut it off just after the skull with a strong blow of a sharp knife.
   • Another way is to insert the blade just after the skull and cut the spine and vertebrae. This "nerve transection" is less messy, but is not recommended if you have experience with fish anatomy.
5. Destroy the brain instantly. Even after decapitation, the fish can still live for a while. Ensure a quick death by immediately inserting a sharp awl or knife into the brain between the eyes. Push forward and back to destroy the brain and the end of the spine.
   • You can search online for the most effective point among various edible varieties that you need to stick the awl into.

Tips

• A fish that has been euthanized can spread disease or poisonous euthanasia. To dispose of it safely, you can burn it, bury it deep and far from water, or wrap it in paper and dispose of it in the trash. Do not flush the fish down the toilet.

Warnings

• Do not hurt the fish because you are in a hurry and do not perform the euthanasia properly. In low doses, some of these chemicals are painful rather than deadly, so do it right.
• Make sure your fish cannot be cured or saved, or is really in pain. Don't euthanize a fish because you don't want it or because it has some mild mold. Tuberculosis is an example of when euthanasia is acceptable.
• Do not use any other method without consulting a veterinarian. Flushing, choking, or putting in the microwave are inhumane methods. Freezing or cooking are humane for some species, and extremely painful for others.
• Some fish can behave unimaginably or energetically shortly before falling asleep, especially when using clove oil. This may or may not mean that the fish is in pain. The drugs mentioned in this article cause this less than other drugs.