Humane method of Euthanasia for sick fish

The question of a humane method of euthanasia for our beloved fish have come up many times in the general forum. When the time comes after unsuccessful attempts at healing results in no improvement for our fish, it may come the time to think about putting the fish out of its misery and pain.

 

It's been awhile since this topic has been thoroughly examined on Fishlore, and the information I'm seeing from veterinary groups is a little bit different than it was the last time I saw it, so I'm starting a new discussion/thread.

The specific point is to make sure that we know what options we have for humane euthanasia.
What I mean by "humane" is a death that is either extremely quick or relatively painless/stress free. It does not mean that the death doesn't offend our human sensibilities. That being said, we also won't be going into gory detail on anything.

Let's first look at some inhumane methods of euthanasia.
The number one thing not to do is flush the fish. This is incredibly traumatic, as the fish could conceivably survive, conscious, as it gets battered around the pipes.
Other things not to do are putting the fish on/in crushed ice, putting the fish in the freezer, or putting Alkaseltzer/soda in the water with the fish.

One of the best methods of euthanasia available to most aquarists is the clove oil method.
Move the fish to a small tank (about a gallon of water will do for most fish, though some very large fish may need more).
Take a pint jar and fill with water from this container.
Add three drops of clove oil.
Put the lid on the jar and shake vigorously until you have a complete emulsion (the oil is totally mixed in with the water).
Slowly add back into the water, stirring gently with your hand.
Once the fish has stopped moving, it is sleeping. At that point, you can either add vodka to the water, or you can add another six drops of clove oil. If, after 30 minutes, the fishes' gills are still moving, add more vodka or a couple more drops of clove oil. When the fish's gills don't move for ten minutes, the fish is deceased. (Yes, ten minutes is a long time, but it's the amount of time vets say is needed to insure the fish is actually dead.)
Note: Some vets say that the preceeding is not an acknowledged method, due to lack of testing. I argue that the number of times it has been done by aquarists is testing, and it is almost always a peaceful drop into sleep.

Another method that will be incredibly simple to some aquarists is an overdose of CO2. If you have a pressurized CO2 tank, vigorously bubble it into the holding tank (I'm sorry... I can't find an explanation better than "vigorously bubble," but I would personally take this to mean "Attach the CO2 tube to an airstone and turn the valve up until there is a good curtain of bubbles in the tank"). This will cause the CO2 to replace the oxygen in the water, and the fish will pretty quickly fall into a coma.
Again, the CO2 needs to be kept up for at least ten minutes after the last gill movement to insure the fish is deceased.
Note: The preceeding method does not work for labyrinth fish or any other fish with a lung-like organ. The fish will simply surface and take a breath of air.

The method that has longest been supported by vets is an overdose of anesthetic. However, many aquarists do not have access to these drugs, and even if they do, the cheapest of them is usually incredibly expensive (I've seen $20 for a 2oz bottle). This is the reason that other possibilities have been explored and found.
Still, if you happen to have access to aquatic anesthetic, follow the dosing instructions until the fish falls unconscious, then gradually add more to the water until respiration stops. Again, ten minutes after the final gill movement is necessary. One source said that leaving the body in the anesthetic bath for 2 hours is a good way to insure that it worked.

Now we start getting into the methods that are, for one reason or another, questioned:

One method is the chilling method. Until very recently, vets have said that this is not a humane way to euthanize fish, as ice crystals can build up in the muscles and cause extreme pain before unconsciousness occurs.
I've found a slight update to this.
With fish smaller than 2", rapidly chilling the fish causes a coma quickly enough that there is very little discomfort to the fish. Put the fish in a small container filled with a small amount of warm aquarium water. Place the small container in a larger ice-water bath (you don't want the ice-water in the container, you just want the ice water to cool the container)
Personally, I would leave the fish in the ice-cold water for a very long time (hours), to be absolutely sure.

A possibility that many on this forum find distasteful (to the point that it is often argued that it isn't humane) is decapitation followed by pithing.
If you don't know how to effectively pith a fish, then it is best not to use this method.

Not all of these methods are appropriate for everyone. That's why there are so many different ones. If it is necessary to euthanize a fish, work with the method that is the least uncomfortable for you. Some aquarists are also fishers by hobby or by trade, and the last method is something with which they have both practice and a certain comfort with, and this is completely fine. Some aquarists want their fish to simply "go to sleep." The method used to do this will depend upon how much they want to spend and/or what they have on hand.
As long as a humane method is used, please don't criticize others for using it, especially given that they just went through having to euthanize a pet. Even if an inhumane method was used, best to very gently point out, for the future, that there are better ways to euthanize fish.

Sources:

American Veterinary Medical Association Guidelines for the Euthanasia of Animals
(scroll to the bottom for PDF)

 

looks like a way to torcher the fish, how do you know the fish is "sleeping" since fish sleeps but still able to move. its just like, paralyze the fish then seep cyanide because they are "sleeping"

 

Which looks like a method of torture?
All of these methods have been tested by people with hefty biology backgrounds. One of my primary sources is a medical paper written for the purpose of promoting ethical euthanasia in animals for multiple purposes (slaughter for food purposes, preparation for testing of lab animals, and veterinary euthanasia). Another is a paper written specifically by a marine biologist with a doctorate in the field. I can't tell the difference between a paralyzed fish and a comatose fish, but these people have equipment and procedures to test just that.

 

Very good update sirdarksol... much needed.

 

Thank you, Sirdarksol for a very informative and well written essay on a touchy topic.

Unfortunately, this is a subject that will spark raw emotions on both sides of the fence.

Plain and simple this is an issue that we all will face at some point in our fishkeeping life. Where you stand on this issue is irrelevant. This is simply pointing out methods should you choose to take this difficult and heartbreaking path.

Keep in mind this is an primarily an informational forum. Yes, there are some areas for fun and games as well as off topic conversations, but this is not one of them.

This thread was clearly labeled to inform members what the topic was. The information is here for those who may need it. If you have no interest in, or a need for euthanasia, and you are simply coming on to this thread to voice your personal opinion and stir up discontent, then YOU are wrong and probably borderline on violating the forum rules.

We have all been united here due to a love for a common hobby. Let's keep personal opinions and political views aside. I know it's difficult to keep such a difficult subject sterile and scientific, but let's try to remain neutral and professional.

That's just my 2 cents.

 

Very informing! Haven't had to do this yet but I'm sure I will eventually.

 

Thanks for taking the time to really delve into this topic. I'm hoping I never have to do this, though, I'm sure I probably will at some point or another. Thanks again.

 

Wow! I feel really bad because in the past, when my sick fish were dying, I just let it happen naturally, or flushed. Thank you for letting us newbies know there is a humane way of dealing with this.

 

Wow! I feel really bad because in the past, when my sick fish were dying, I just let it happen naturally, or flushed. Thank you for letting us newbies know there is a humane way of dealing with this.

No worries about it. The reason we're here is to learn. Honestly, I haven't often euthanized my fish. Most of the time, I go with the "happen naturally" line of thought. It's difficult for me to decide when illness has gone too far.
And the concept of flushing sick fish is part of our culture. It's something that groups like Fishlore are trying to change, but we understand that the concept is there and don't hold it against people who use it when they haven't been given information about what it really does.

 

I have had to use the clove oil method a couple times. If done right it seems to go smoothly and does not appear to be traumatic to the fish. After waiting the 10 minutes for no gill movement I do still place the fish in the freezer, just to be double sure. Clove oil is also readily available, and usually reasonably priced, at health food and lifestyle stores and sometimes at the regular market. As unfortunate as it is to have to use any method of euthanasia it is better than allowing suffering.

 

Thank you for this information. While I have yet to need to euthinize my fish about 6 months ago I found myself researching the topic for a relivent reason. One of my 6 year old Angels appeared to have suffered a "stroke" ....what was acctually wrong with him I never found out but his eye on one side "blued / blacked" out and he appeared to have paralisis on one side. I called the aquatics vet but they would not "diagnose" over the phone and the trip to there office is two hours from where I live so that was not a reasonable option for an already deathly ill fish.

I could find very little information on humane methods but had decided to go with the chilling method. They only one I could find.

Gabe passed away before I acctually performed the process, somewhat thankfully.

But had I needed to do this it would have been nice to know the options.

Thank you.

 

Can anyone tell me where to buy clove oil?

 

Can anyone tell me where to but clove oil?

I believe health food stores have it

 

Thanks. One store said they sell the essential oil is that it?

 

Essential oil is pure, so yes.

 

Thank you so much for this clear and concise information. I have to perform this sad task for my son's betta, who has a large tumor and has been suffering for weeks now . He looks like his skin is going to pop open, and the clove oil method sounds like a much more peaceful way to go. I appreciate you taking the time to write this...

 

^ i'm so sorry. I had to do that to all of my betta's.. I miss them. <3

 

I really don't want to kill my best fish..

 

I really don't want to kill my best fish..

I never do, I just let them go naturally.

 

I've tried medicating, letting them go "naturally," and clove oil, and I've finally decided on the latter when I see an impossibly curved spine and a mouth so ragged that the fish can't eat. It's never easy for me to do, but the fish go limp immediately and don't struggle, so they are much less stressed out that any of the ones I've tried medicating. I've decided that while it's a difficult decision for a pet owner to make, I can't let a fish suffer a slow and painful death when a human who has the resources can get pain meds.

 

Can you use the clove oil method with a snail?

 

I printed out the article. I will soon have to euthanize a large comet goldfish. He came home over spring break years ago and I still have him. A local small vet said that tumors are common in comets and mine has a large tumor just smaller than a golf ball on his side. He seems not bothered by it, but how will I know it is hurting him? Are there signs with the fins? etc.? Thank you for covering this information.

 

I printed out the article. I will soon have to euthanize a large comet goldfish. He came home over spring break years ago and I still have him. A local small vet said that tumors are common in comets and mine has a large tumor just smaller than a golf ball on his side. He seems not bothered by it, but how will I know it is hurting him? Are there signs with the fins? etc.? Thank you for covering this information.

I've had several fish and dogs with untreatable tumors over the years. What we've done is keep them comfortable and taken care of them until they were unable to eat, which is usually a sign that they've reached the point where they're suffering.

 

I wish I knew this last July when one of my guppies had a badly chewed tail and couldn't even swim. I think he was tramatized when we were trying to put a female in the breeder and got caught in the net and that didn't help.

 

Thank you for posting this. I hate losing any animal, but I hate seeing them suffer more, and it's really comforting to know I have a reference of how to handle a dire situation.

 

I've used clove oil to sedate puffers before (clipping is traumatic without it), and there is a fine line between sedation and death. Thank you for the information.

 

I've used clove oil to sedate puffers before (clipping is traumatic without it), and there is a fine line between sedation and death. Thank you for the information.

Actually, I've been in the room (at my own request) during the euthanasia of 2 of my past cats. The method generally used is to sedate them, then keep giving them the sedative until they just stop breathing. If your animal is suffering (one of my cats had an inoperable brain tumor and one had feline lymphoma and had had a series of grand mal seizures) it's really a gentle way to end their pain.

 

I read that one of the best methods is using clove oil to put them to sleep, then placing them in a baggy in the freezer. This was they are completely asleep when the rapid chilling occurs.

On the same article a Coast Guardsman recalled having had to be rescued from waters whose temperature was rapidly dropping (not sure of the circumstances), because he began to go into a sense of euphoria and was on the verge of hypothermia without the sense to get out of the water.

Apparently this sense of euphoria is common among people who have been on the verge of death from drowning in cold waters. At first the water feels awful, and then it begins to feel warm and a sense of euphoria is felt.

Not sure if this is the same for fish or not, but at least the clove oil would put them to sleep first, and if it didn't happen to work quite as well (How do we tell if the fish is asleep or just paralyzed?) they may not be in pain for longer than a short while.

 

I always used clove oil then vodka, kills them quickly and humanely, I hate the idea of freezing fish. Euthanasia is always a hard decision

 

Necessary, but I really can't even read this forum all that much. Pretty tough road.

 

I printed out the article. I will soon have to euthanize a large comet goldfish. He came home over spring break years ago and I still have him. A local small vet said that tumors are common in comets and mine has a large tumor just smaller than a golf ball on his side. He seems not bothered by it, but how will I know it is hurting him? Are there signs with the fins? etc.? Thank you for covering this information.

I had a fancy live for 15 years with huge tumors on him. He actually passed when I moved across the country (to much stress I assume)