How to Euthanize a Fish? A Humane Way of Offering Eternal Sleep to a Sick Fish

How to Euthanize a fish is the most troublesome dilemma of a fish keepers’ life. Euthanasia is a Greek word meaning- good death, which comprises several active and passive domains. Fishkeeping is a wonderful hobby. You get to enjoy the blossoming of your beady friends in the water. You are watching them grow and make a tiny finny family. You know the joy of bringing a new fish breed, a new member in the family from the vendor into your aquarium. You look after them, care for them, trying to offer the best shot at life. However, sometimes, you will be faced with a difficult decision. Sickness, inherent or acute, affect all forms of life. It can affect you, and it can affect your little fishes. When your fish stand at the horizon between a painful life and eternal comfort, the choice depends on the course of how to euthanize a sick fish. When your fish is suffering, and clearly in the worst periods of its end of life, you will realize euthanasia is an option as a last offering to care for them and relieve them from the suffering.

The experience of losing your pet is heartbreaking, and it shatters you completely. There is no other way of saying it. But if you choose to allow them a reprieve from the pain, there are certain things that you should be aware of, to do it right for your finny friend. While some fish keepers sternly believe that allowing nature to take its course is an option. The choice is yours, and whatever you choose to do, we only hope to guide in the best possible ways to do things. Should you choose euthanasia, here’s a guide on how to humanely euthanize a fish, along with some more routes on how you can ensure keeping your fish tank’s inhabitants healthy and happy.

When and Why is It Necessary to Euthanize a Fish?

When you are just beginning as a fish keeper, it is hard to think that you will come across a time when you will have to deliberate on how to painlessly euthanize a sick fish. Your fish tank is an ecosystem, pure biology, and that biology is highly prone to numerous aquatic diseases or towards natural senescence. This ecosystem is also vulnerable, anything and everything can tip of the health of your fish, or it might be something more inherent carried from a sick finny parent. Sometimes, you must ponder over how to know when to euthanize a fish because of this inevitable vulnerability of the system you care for and love so dearly. Perhaps, a rather aggressive fish injures a docile, slow swimming fish species so brutally that it is beyond your capabilities or the vets to nurse it back to health. 

If you stick with that sentiment, it does create a sort of terror in you as a fish keeper, as their guardian. In such a situation, the deliberation of how to humanely euthanize a fish becomes your reprieve. Here are a few more unfortunate events when you will be considering euthanasia as an option to relieve your aquarium of its terrible fate, should you decide to assist nature in its course.

A large number of diseases in fish can be so fatal and painful that you might find yourself thinking about how to euthanize a fish. Some of these aquarium diseases include chronic wasting disease, dropsy, Hexamita infection, neon tetra disease, etc.

You have a young fish that shows unusual biology, which can be a direct effect of genetics and may worsen as the fish grows, leaving it at the hands of a painful death. To relieve your young fish from these devastations, you might consider the deliberation on how to euthanize a fish humanely.

An older fish, close to its end of life, because of an unstable immune system, is prone to catching several diseases if prolonged, compromising other fish species’ health in the tank.

By taking one of the routes on how to humanely euthanize a sick tropical fish, you are hoping to prevent a disease outbreak in the tank. As seen in the case of neon tetra disease, several fish are at a high risk of developing the same health anomaly should they come across an affected fish or get in contact with it.

At the heart of this subject lies the awareness about the difference between the right ways and wrong methods on our pondering of how to euthanize fish. In the next section, we will discuss the best practices on how to gently euthanize a fish with elaborate conjectures on why one method is kinder and gentler than the other.

The Best Course of Actions for How to Euthanize a Fish

According to ethics, it can be said that inducing a state of euthanasia is indeed not strictly an act of veterinary surgery and can be performed by an expert fish keeper who is sufficiently trained on the mechanics of how to euthanize a sick fish. It is essential to understand that this practice’s essence lies in offering comfort to a suffering fish. Hence, from the very first step to the last, it is of the utmost criticality that you ensure a gentle hand. There has been substantial research and debate on the most humane method of euthanizing a fish. To offer you a reliable guide, we went through several professional and public opinions of both expert fish keepers as well as those from veterinary professionals.

Here are the safest, gentle, and effective remedies on how to euthanize betta fish or any other fish breed.

Alternative 1 on how to euthanize a fish- Overdose of Anesthesia

As animals, all fish species exhibit several patterns of physiologic stress. If you choose to use the first alternative on how to gently euthanize a fish, there are several factors that you must consider. Several routes have been recommended by expert fish keepers who have prior experience on how to humanely euthanize fish.

The first method is also one of the most vouched for- TMS or Tricaine Methanesulfonate, more commonly known as MS222, or Finquel is readily available at your local pet specialty store. According to experts, using double the amount of what you would use to anesthetize the fish would be enough to euthanize it. It is important to note that TMS is also one of the few euthanasia substances that are easier to procure as the FDA approves it as a product exclusively used to euthanize a fish. 

The second substance falling under the alternative of how to painlessly euthanize a fish is Benzocaine Hydrochloride. Unlike MS222, which can be easily procured from your local pet store, you will need a prescription from your veterinarian to use Benzocaine Hydrochloride as a route on how to humanely euthanize a pet fish. The heralded authority on pet keeping and the best delegate of the humane way of euthanizing pet animals – AVMA, advocates the use of Benzocaine Hydrochloride as one of the most reliable routes of how to kindly euthanize fish. However, it is essential to note that Benzocaine Hydrochloride should not be used directly. Since the product is insoluble in water, you need to use an ethanol or acetone mixture along with water and Benzocaine hydrochloride, which in essence, is similar to the methods dictated by how to euthanize a fish with vodka.

How to Euthanize A Fish Using Clove Oil?

It is hard to make out the accurate concentration of the clove oil in a bottle you purchase. You must inquire from the seller about the exact concertation as it determines the rate of success and how much clove oil to euthanize a fish you would consider using. You can begin by adding a few drops of clove oil into the container carrying the sick fish. Gently stir the water in the container to mix the ingredients evenly. 

The most important of this deliberation on how to euthanize a fish using clove oil depends mainly on your observation. If your fish’s gills are still in motion, it is highly likely the animal is simply knocked out but not euthanized. The moving gills are a direct sign that the clove oil has successfully put the fish into a state of unconsciousness. 

If you see the fish stirring after a few minutes of adding clove oil, you will need to increase the amount of clove oil you used. The best method of following up with how much clove oil to euthanize a fish is to use a stronger dose. Take out some water from the original container and add twelve more oil drops to the original mixture. Stir the water until the clove oil has been mixed in thoroughly. Add the new mix with a higher dose of clove oil to the original container with the fish.

It is best to wait for a minimum span of 30 minutes to check how well the method of how to euthanize a fish using clove oil has worked so far. If you don’t detect any movement, especially in the gills, it is safe to say that the clove oil alternative on how to euthanize a fish has worked just fine, and you are fish is in eternal sleep, free of all pain. Clove oil causes fast hypoxia making the fish unconscious and gently euthanizing them when they are sleeping. It is essential to stress that you must keep an eye on the movement of the fish, ensuring there is no movement after a considerable amount of time has elapsed. 

Here is a short video guide on how to euthanize a fish using clove oil

Alternative 2 on how to euthanize a fish- Barbiturates

The Barbiturate injection is one of the more professional methods on the subject matter of how to euthanize a fish.  Expert fish keepers or vets more frequently use this method. The biggest issue on this alternative on how to gently euthanize a fish using barbiturates is quite difficult as it is hard to get your hands on these products. For this route, you will have to ask for help from your local veterinarian. It is also important to note that the Sodium Phenobarbital is the right product for taking this route on how to humanely euthanize a fish. Other barbiturates injections can cause pain to your fish during the process.

Alternative 3 on how to euthanize a fish- Physical Euthanasia

The following routes on how to humanely euthanize a pet fish are to be practiced only when you have fast reflexes, and you have a robust knowledge of the fish’s anatomy. Methods, including decapitation, stunning, or brain pithing, should only be undertaken when you know how it is accurately carried out. If you find this method uncomfortable, as many fish keepers do, it is best avoided, and you can choose the methods described above, such as how to euthanize a fish using clove oil.

How to euthanize a fish from a fish tank using the stab and stun method?

The stun and stab method on how to gently euthanize a fish is a good way of relieving the sick fish from a painful life. However, care must be taken to go through with this method only if you have prior training and experience.

The goal is to hit the fish just above the eyes with a club or any other hard object. We know, stunning your fish by smacking it on its head does not sound like the most humane alternative on this list of how to euthanize a fish. However, when done correctly, it means a quick death. Sometimes, if the method leaves the fish alive for a moment, it is best to relieve it from the suffering by inserting a sharp object such as a knife into the fish’s brain between its eyes.

Once, few fellow fish keepers and I kept into this deliberation of euthanasia and how to humanely euthanize the fish. The sentiment is not so hard to understand; for most fish keepers, it is hard to see their fish suffer for a longer time, which is one of the most fundamental reasons behind fish euthanasia. The decision also depends on how accurately you can take on this responsibility. The essence of how to euthanize a fish lies in understanding that there are right and wrong ways of going about it. Here are some of the redundant methods that are not necessarily humane.

Learn more about how to euthanize a betta fish in this video

How to Euthanize a Fish? – Methods You Should NOT Use!

The essence of this post is to give a guide on how to HUMANELY euthanize a fish. Unfortunately, some of these wrong methods are still in use by individuals who don’t know better.

First wrong take on how to euthanize a fish- Flushing

Flushing the sick fish in the toilet is the most disrespectful and inhumane form of euthanasia of going about the deliberation of how to safely euthanize a sick fish. The method is often practiced by those interested in the hobby but unaware of its inherent nature, especially those who bought a readily available betta fish, unaware of the proper fish care and maintenance procedures. When the fish succumbs to a disease or suffers from an unbalanced nitrogen cycle in the aquarium, they are left to deliberate over the possible methods on how to euthanize a betta fish? When a fish is flushed in the toilet, it experiences a slow torturous death, suffering from its existing ailments and those inflicted by the toxins present in the sewage water. Even when it seems like an easy way to go, you are only getting rid of the fish. A true fish keeper would never agree with such a course of action.

No fish or any other creature would want an end surrounded by human excreta!

Second wrong take on how to euthanize a fish- Ice Water

Depending on your fish’s biology and size, using ice water as a form of euthanasia can be effective or ethically wrong. Considering the controversy, we advise that you avoid using this method.

Certain studies show that introducing a species of the zebra danios fish in an ice water bath at around 39 degrees F can be an excellent way to go about the quandary of how to humanely euthanize a fish. Following the studies’ inferences, perhaps, the method works for fish species measuring around 2 inches or smaller.

However, as it is often noted, the ice bath causes a frost formation in the sick fish’s gills. Frozen gills can cause your fish more pain. Hence, it is not a correct way to follow up on the deliberation on how to euthanize a goldfish, sturgeon, or koi fish since these fish types are tolerant to cold water conditions and may survive the process of euthanasia.

Third wrong take on how to euthanize a fish- Carbon Dioxide

Carbon dioxide is another unadvised method of killing a fish, but there are several deliberations that make this route so. It is indeed true that carbon dioxide will eventually kill your fish. However, when there is a reduced amount of oxygen in the tank and more carbon dioxide, the sick fish might spend its last moments stressed and suffocated. When we discuss how to gently euthanize a fish, this doesn’t seem like a gentle way to go about it.

Fourth wrong take on how to euthanize a fish- Boiling Water

Adding your ailing and sick fish into a pot of boiling water seems like a scene from a movie with a “cuckoo in the head protagonist.” The only sentiment about this method, it is inhumane even to consider doing it, let alone carrying it out for real!

Fifth wrong take on how to euthanize a fish- Vodka

Using vodka as a means of euthanasia is considered inhumane, as the strong concentration of undiluted alcohol will burn your fish’s gills first before killing. As we said, the concern is how to GENTLY euthanize your fish! Having gills set ablaze in a shot glass full of cheap vodka is an inhumane method and should not be considered. Asking for a detailed guide on how to euthanize a fish with clove oil and vodka as we are creating a water bath with diluted ingredients. The clove oil acts as a sedative taking away all the pain from the sick fish, while vodka swiftly euthanizes it. This take is entirely different from using a high amount of undiluted alcohol!

How to Euthanize a Fish? – FAQs

How many drops of clove oil to euthanize a fish? Adding 12 drops of clove oil in one gallon of water (dechlorinated) effectively induces euthanasia in fish. It is important to note that clove oil is insoluble in water; hence you can create an emulsion by adding a small amount of water and 12 drops of clove oil in a leak-proof jar. You need to shake the jar vigorously to create an emulsion successfully. In order to understand proper euthanasia for fish with clove oil, you must know the exact number of how much clove oil to euthanize a fish.

How to euthanize a goldfish? The best method of euthanizing a goldfish is by the use of clove oil. Clove oil is readily available at local pharmacies and supermarkets. As the clove oil is proven to introduce unconsciousness and simultaneously death quickly, it is one of the most humane methods of relieving your fish from the excruciating pain. 

How to euthanize a large Oscar fish? Using stun and stab or brain pithing methods by a trained and experienced fish keeper is the best method of euthanizing a large Oscar fish. Due to the large size, it is crucial to observe the fish for any movement to ensure that the fish is euthanized effectively. You can also consult your local veterinarian for using the anesthetic overdose method to euthanize the Oscar fish if using physical euthanizing methods are not the best route for you. Clove oil is another effective alternative for fish keepers wishing to relieve their Oscar fish from an ailing and painful life.

How to humanely euthanize a betta fish?  Due to the small size of the betta fish, there are several methods that you can use to induce euthanasia for your sick betta fish. Clove oil is a good alternative as it is readily available and causes quick death. Fill a container with dechlorinated water and add 1-3 drops of clove oil in the water. Use another container to add 12 more drops of clove oil in a small amount of dechlorinated water and shake it well. This will help create an emulsion as clove oil is insoluble in water; add the emulsion to the original container containing a few drops of clove oil. Mix the ingredients well. Place your fish in the container and observe for 30 minutes. Check for any possible movements in the fish. If the betta fish does not move, it has been euthanized successfully.


For a fish keeper, experiencing the death of a fish that you cared for can be a heartbreaking experience. However, watching your fish suffer from an injury or an ailment is the worst time for both your little fish and you. In such a case, the best way to ensure that you gave your all to help your finny friend is to ensure that you gave it a fighting chance, you used all the possible remedies to cure its sickness and pain. Alas, if there comes a time when you are left with nothing that can help your fish. Or if the fish has stopped fighting, succumbing to a terribly painful life, euthanasia seems like the only comfort you can offer them. There are several answers to the deliberation – how to euthanize a fish. However, our goal is to give you solutions on how to HUMANELY euthanize a fish. There are swift and effective methods to help your fish escape its terrible fate of a painful life, inducing an eternal state of sleep. You must also understand that are some ethically wrong, inhumane methods too; hence, before making a firm decision, learn about the gentle ways of offering peace to your finny friend.

Sharing is caring!

Leave a Comment