The vodka ensures that the fish expires.
There comes a time in every aquarist’s life when a fish that can no longer recover from illness or injury must be euthanized. This is not an easy task, but it can be done in a humane and peaceful way, without stress for the fish or the aquarists. The best method is a two-step process. First, anesthetize the fish with clove oil so that it sleeps and doesn’t feel pain; then introduce a clear grain alcohol like vodka to make sure the fish doesn’t wake up.
Clove oil anesthetizes fish.
This method is commonly confused with mixing clove oil and vodka. This is incorrect. The clove oil should be introduced first, allowing the fish to fall asleep before the vodka is introduced. Vodka is stressful for a fish that is not anesthetized.
Clove oil, or eugenol, is available at most drug stores and is sold as a toothache remedy. It has been used as an anesthetic for fish in surgeries and tagging procedures for years. Clove oil numbs the fish and ensures that it does not feel pain. However, the fish can be awakened from this sleep if it is removed from the clove bath. The last step of adding the vodka will ensure that the fish expires.
Fish should not be flushed down the toilet.
For fish up to 3 inches long, a few simple steps can be followed. The owner of the fish should add some of the tank water to a measuring cup or bowl. The amount of tank water added to the cup or bowl should be measured and recorded. Next, the fish must be placed in the container. If the fish is in a clear glass, a dark towel placed around the glass can calm it down.
Fish can easily be humanely killed.
Next, the owner should fill a small, clean jar or bottle with water from the tank, leaving a little space at the top. A bottle of baby food or a bottle of pills can work well for this. Then you need to add 1 drop of clove oil to the vial or bottle, cap and shake the vial vigorously. The clove oil should emulsify, leaving the water milky white.
Approximately 1/4 of this emulsified mixture should be poured into the tank. The fish will begin to fall asleep as it begins to fall asleep. The fish should sit for about 10 minutes.
The fish should be resting on the bottom of the tank when it falls asleep. It will appear dead, but if you look closely, its gills will breathe once every few seconds. If after 10 minutes the fish is still coming out of the bottom and swimming intermittently, the owner should take the vial or bottle of emulsified clove oil, shake again and add the same dose to the container of fish. You must wait again for the fish to fall asleep.
Once the fish is sleeping on the bottom, add 20-25% white grain alcohol. For example, if the fish is in 8 ounces (240 ml) of water, 2 ounces (60 ml) of vodka should be added. The fish must remain there for at least 20 minutes.
After 20 minutes, the fish should be carefully checked for any gill movement. If there is no gill movement for a period of 60 seconds, the fish has expired.
For large fish, the fish should be placed in a plastic bucket or tub of tank water; again, the amount of tank water used should be measured. The dose to mix in the pot will be 10 drops of clove oil per gallon (3.78 liters). For example, if the fish is placed in 3 gallons (11 liters) of tank water, the jar should be filled with tank water and 10 x 3 = 30 drops of clove oil.
After vigorously shaking the jar, the owner of the fish should slowly add the entire mixture to the bucket or tub containing the fish. Then it should be gently mixed. After the fish is sleeping, the above instructions for adding 20-25% vodka should be followed.
To eliminate the vodka and clove oil overdose procedure, the fish must first be put to sleep as mentioned above, and the owner must wait 10 minutes for the fish to settle to the bottom. A lethal overdose of clove oil is 50 drops per gallon (3.78 liters), or 5 times stronger than the initial dose that anesthetizes the fish. Using the same example, if the fish is in 3 gallons (11 liters) of tank water, the lethal mix in the jar will include 50 x 3 = 150 drops of clove oil. It should be administered in the same way, first shaking the bottle before placing the mixture in the container of fish.
Once all the mixture has been added to the fish container, the owner must wait a few hours. Finally, he must ensure that there is absolutely no gill movement by observing the gills closely for at least 60 seconds at a time. If any gill movement is observed, more emulsified clove oil should be added.
Using clove oil alone is not recommended, because even though a fish may appear dead, it may recover once removed from the bath. Clove oil is a preferred anesthetic precisely because it is difficult to overdose with a fish. Therefore, users must be especially diligent when using clove oil alone, making sure the fish is actually dead. It is much safer to use vodka as the final step.
Unacceptable methods of euthanasia include freezing, mincing, removing the fish from the water, or flushing it down the toilet. These methods are slow, tortuous, stressful or violent. Clove oil followed by vodka is cheap and humane; the fish goes to sleep and just doesn’t wake up. Hopefully, most people will rarely have to do this, but when someone does, it’s at least reassuring to know your fish doesn’t have to suffer.