7 Humane Ways to Euthanize a Fish at Home

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As a fish owner, it is unfortunate to know that euthanasia is essentially part of the job. Learning how to euthanize your fish humanely is a skill you will have to master if you are planning on becoming a long-term fish owner, be it as a hobbyist, pet owner, or researcher.

How you euthanize your pet fish will depend on various factors like the type of fish and its size. It is essential to know that even though some crude methods work, taking the fish down more humanely, swiftly, and without pain is also good.

how to euthanize a fish

The fish was once your Goldie or Sunny, or Little Betta, and the good news is there are several proven, swift, humane ways to euthanize the fish.

Read to know why you may want to mercy kill your fish and what veterinarians have to say about it. Get to learn of the best fish euthanizing methods, both traditional and modern humane ways, and some unconventional ways you must avoid.

Reasons Why You May Have to Euthanize Your Pet Fish

So, you may be wondering; My fish is dying. Is it suffering? Should I euthanize my fish?

It goes without saying, killing a fish because you do not want it anymore is not a good reason to euthanize the beautiful creature. Most cases warrant euthanization due to debilitating fish illnesses like dropsy or physical injuries that hinder the fish’s movements.

Pineconing – Dropsy

Dropsy is among the many diseases that can cause fish to have a pinecone shape. The shape sets in when the fish has suffered many illnesses and injuries, leading to the formation of a pinecone appearance with a distended cavity and round shape.

The pineconeing scales get flared away from the body on both sides of the fish. It is usually hard to pinpoint the main underlying problems at this stage, which is why it is a tale tell sign to euthanize the fish and avoid prolonging its suffering.

However, you should check in with a professional to see whether the underlying diseases can be treated. You will be surprised to know how many fatal illnesses a resilient fish can overcome.

Old Age

Every animal has a particular lifespan, and you probably already know how long your fish will live. Clear signs that old age is taking a toll on the fish include an increased number of fatal diseases, fading colors, more naps than usual, thinning, curled fins, spongy textures, and general skin discoloration.

Physical Deformities and Poorly Developed Physique

It is also common to see fishes that had a bad bet on life from the word go. Physical deformities like curved spines, abnormal growths, and scaling are just a few of the many conditions that can make it hard for your fish to survive in certain environments. If you can tell the poor guy isn’t going to make it, you may want to consider mercy killing him.

Fish That Cannot Eat or Swim

Apart from illness, the leading cause of immobility in fish is stressful tank conditions. Once your healthy fish stops swimming and eating, it may be far gone for you to do anything to change its state.

Causes of stressful tank conditions range from improper water conditions like high ammonia levels, competitively environment with other fish, improper diet, and improper tank treatments and cleaning, among many more.

If your fish exhibits any of the above cases, you may want to analyze how far the fish is gone before proceeding to follow one of our best humane ways of euthanizing a fish.

What Is the Most Humane Way to Euthanize Aquarium Fish?

So, how do you put a fish down humanely? What counts as humane? The debate on whether fish feel pain has lasted generations, but we can all agree we do not like to see our pets suffer.

For humane, safety, and accessibility purposes, it is prudent to stick to the AVMA (American Veterinary Medical Association) approved guidelines on euthanizing fish and other aquatic life. The most recommended ones on the list include immersion and injection, using anesthetic and euthanizing chemicals.

Below are the proven humane methods of euthanizing an aquarium fish:

1. Immersion in 100% Pure Clove Oil – Most Recommended & Most Popular

Clove Oil

Euthanizing fish with clove oil is the most popular and accessible method. Clove Oil is easily accessible in most regions, and you can find it in your local supermarkets, health food centers, or local pharmacies/chemists.

It is an AVMA-approved method, but the FDA prohibits it in case the euthanized fish are going to be consumed afterward.

A small dose of about 0.4ml per liter is enough to kill the exposed animal. Clove Oil is a natural and cheap product that acts as a fish anesthetic at low doses. In high doses, clove oil is toxic to small fish and can be used to euthanize them.

Sticking to the purest form (100%) of Clove Oil is important since less pure forms can severely affect the fish without killing them.

For better results, it is also recommended you avoid feeding the fish for at least 12 to 24 hours prior. This helps reduce regurgitation and waste products that can affect the drug’s effectiveness. It is also important to measure the clove oil plus water mixture according to the size of your fish; five drops of clove oil are more than enough for fish below 4 inches.

Follow this step-by-step guide to euthanize your pet fish with 100% clove oil:

  • Take your fish from the aquarium and place it in a bath filled with water from the aquarium. Ensure the bath is huge enough for the fish to move around freely and comfortable enough to avoid any shock or stress.
  • Proceed to make a milky white solution using the clove oil. Take a spare container with a lid and drop about five drops into it. Add water to form a mixture of about 0.4 ml of clove oil per liter of water. Close the lid and shake the mixture till you get a cloudy color.
  • Take the cloudy mixture and add it to the fish bath. Stir for several minutes as you watch the fish get knocked out. The fish is not dead at this point but just unconscious. Feel free to add more clove oil mixture if the dish is still active after a couple of minutes.
  • Proceed to add an overdose mix of the clove oil, using more than three times the original dose. Shake the water and oil mixture well and add it to the fish bath.
  • Stir for more than 30 minutes, and the fish should successfully pass on painlessly.

2. Overdose on Prescribed Anesthetics Through Immersion

This AVMA-approved method follows the same clove oil step-by-step guide but uses stronger chemicals. One downside to these chemicals is that most of them are not as accessible as clove oil. They have controlled substances and medically restricted drugs used by veterinarians.

An exception is Tricaine Methane Sulfonate (TMS), a highly recommended anesthetic for the job accessible at pet stores and online shops. Use a double dose for the second mix instead of a triple dose to swiftly euthanize the fish.

Other chemicals include Isoflurane, sevoflurane, benzocaine, quinaldine sulfate, and lidocaine.

3. By Injection of Barbiturates

Barbiturates are the euthanizing chemicals most veterinarians use to put down other pets like dogs and cats. It is a humane and quick method but not the most recommended way since it can be painful for small fish.

4. Combination of Clove Oil and Alka Seltzer

Alka Seltzer tablets used to be the scientifically approved method of euthanizing fish in the 1980s. However, modern science has proven that, on its own, the drug can cause major discomfort and pain to the fish.

In case you have a bigger fish, more species, or do not have enough clove oil, then adding Alka Seltzer tablets to the unconscious fish is a humane way to put them down. This is a great option for euthanizing the fish at home since both clove oil and Alka Seltzer are readily available.

Traditional Methods Used to Euthanize Fish

Some of these methods may be quick & painless but don’t you feel bad just thinking about it, especially when we have already proven humane and less problematic ways of euthanizing a fish?

5. Physically Stun and Stab

This is an AVMA-approved cervical cut using a knife after blunt force trauma to the fish’s skull (which causes a concussion). The goal is to quickly apply a blunt force trauma that immediately leads to death or unconsciousness.

You should follow the forceful stun with a pithing stub to the fish’s vital organs to ensure a quick, swift death. It is important to note that this method won’t be easily effective on bigger animals, and experience in the field is recommended.

Albeit brutal and gruesome, the stun and stub have been a pretty effective method in many instances. This is because the fish immediately drifts into unconsciousness or dies on the spot; the stub is a last resort to ensure the fish doesn’t suffer in case it regains consciousness.

6. Swiftly Decapitation

A quick severance of the fish’s head is not humane but somewhat a merciful way to end the fish’s life. It is, however, important to follow up the decapitation with a swift pithing of the brain since the fish may still be conscious.

You can also opt to keep the head intact by cutting the connection between the skull and the spinal cord. Insert the knife right below the skull to cut the connection between the spinal cord and cervical vertebrae. Not recommended for first-timers.

7. Ice Water Bath

Hypothermic shock is the process used to euthanize fish in an ice-water bath. It is a quick rapid chilling method that is not recommended for fish that can tolerate cold or cool waters: goldfish and carp are some examples. Smaller fish are also more likely to die by rapid chilling than larger fish due to the faster rate of heat loss from their smaller bodies.

The process is simple:

  • Create an ice water bath filled with 2 – 4 degrees Celsius (36-39 degrees Fahrenheit) water. Ensure the tab is large enough to prevent the fish’s skin from sticking to bare ice or cold bath walls (a truly painful experience for the fish).
  • Proceed to quickly transfer the fish into the ice bath. Rapid killing takes place as first as the first 10 seconds, but a minimum 10-minute exposure is recommended.

Must Avoid Inhumane Ways of Euthanizing a Fish

There are other methods that a lot of fish owners use to kill their pets and dispose of them. The methods below are inhumane, unsafe, and unacceptable, especially provided we have many accessible, humane ways of euthanizing fish.

Flushing Down the Toilet

Flushing the hopeless fish down the toilet may be expedient but can be very costly. First of all, the fish will die a slow, painful death since you cannot tell how long it will survive in the toilet and sewage water.

Secondly, exposure to contagions and other chemicals may lead to illness-inducing compounds that are dangerous, especially in confined environments.

Carbon Dioxide

Carbon Dioxide was an approved method of euthanizing fish and other animals until an EU study proved that the gas could cause asphyxiation and acidic reactions, leading to more excruciating pain.

Boiling Water

It is surprising that some see placing a fish in boiling water as a way of euthanizing fish. It may be confused with the rapid chilling method of an ice bath, but placing a fish in boiling water will do the opposite, painful job.


Did you know that dipping a fish in alcohol is compared to dipping a human being in a tank full of gasoline? It is not fun at all. Immersion in alcohol is painful to fish since the reaction of the alcohol with the fish’s skin causes its organs, like the gills, to burn.

How Do You Know the Fish Is Gone?

There are thousands upon thousands of fish species which makes it hard to have an explicit sign of death in fish. However, common cases in most fish species range from zero gill movement to respiratory failure for at least 30 minutes – 2 hours.

Proceed to look at the eyes to ensure they do not roll when you move the fish from one of its sides to the other. This is because the heart can still contract even after the fish is dead, but the eyes cannot roll when both the brain and the heart have stopped working.

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Final Thoughts

How to safely and humanely get rid of the euthanized fish is the last step of these processes. Ensure you adhere to the local, federal, and state regulations regarding the disposition of dead animals in your area.

A sure way of doing this in most cases is to bag the dead fish in a sealed bag and dispose of him with your garbage. You can also bury the dead animal in your garden, backyard, or house.

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