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#1
Old 04-25-2009, 12:27 AM
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What is the most humane way to euthanize a fish?

We have a young Diamond Tetra who has suddenly gone wacky. One minute he was swimming around without a care in the world. Now he is flying about the tank in an uncontrolled spiral-like pattern, much like a balloon that was blown up and then let go without tying the end. It appears that he has had some sort of fish stroke, as the right side of his body is mostly paralyzed, and is body is kind of curved around to the right. Yesterday I figured he only had a few hours to live. Tonight he is still flailing about the tank. Anyone have any suggestions on how to put our little fish out of his misery?
#2
Old 04-25-2009, 12:58 AM
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Do you have a cat?
#3
Old 04-25-2009, 01:00 AM
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A couple of methods would be so quick they would be relatively painless.

1. Catch it and drop it into a bowl or container of ice water. (Place a bowl of water in the freezer until it just starts to freeze, then break the surface ice.) The temperature shock should kill a tropical fish almost instantly.

2. Drop it into alcohol at as high a concentration you can find. (Vodka would work.) Again, this should almost instantly paralyze and kill the fish.
#4
Old 04-25-2009, 08:47 AM
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I remember discussing this problem with some biologist colleagues, and that's a tough one.

I think that Colibri gave you two very good solutions. There is another one that I can think about, which may sound like a joke but which would actually provide the desired result: use a kitchen blender.

Last edited by Oukile; 04-25-2009 at 08:48 AM. Reason: grammar
#5
Old 04-25-2009, 08:59 AM
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Quote:
Originally Posted by Oukile View Post
I remember discussing this problem with some biologist colleagues, and that's a tough one.

I think that Colibri gave you two very good solutions. There is another one that I can think about, which may sound like a joke but which would actually provide the desired result: use a kitchen blender.
MMM-that's good bass!
#6
Old 04-25-2009, 09:59 AM
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1. Catch the fish in a net and smash the net on the nearest hard surface. Seems brutal but the fish will never know.

2. Decapitate the fish with a sharp knife.
#7
Old 04-25-2009, 10:09 AM
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Quote:
Originally Posted by Baracus View Post
1. Catch the fish in a net and smash the net on the nearest hard surface. Seems brutal but the fish will never know.

2. Decapitate the fish with a sharp knife.
Ach, so sorry, but I'm afraid that this will not work.

Solution 1: due to the light weight of the fish, and the dumping power of the net itself, you will find it difficult to smash the fish hard enough. And the little beast is quite resistant so it may take you quite a few attempts before you manage to kill your fish this way -if this ever happens.

Solution 2: the fish will fight, try to escape, slip around on its slimy skin; you will have a hard time getting a good grip, and it will take you some time before you manage to complete decapitation. If you don't cut your fingers in the process.

Out-of-water fish handling is difficult for you and definitively stressfull for the animal. You want to avoid it as much as possible.

I can, however, suggest an efficient variant of your solution 1. Capture the fish in a small net, then use a large hammer...
#8
Old 04-25-2009, 10:12 AM
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maybe he's just horny
#9
Old 04-25-2009, 11:54 AM
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If it's small, I think the kitchen garbage disposer solves merciful dispatch of life and corpse disposition simultaneously. Fire up the disponser and drop it in. I've seen arguments on my fish hobbyist sites against icewater. Alcohol seems a bit fancy, and not necessarily instantaneous. Smashing is fine but seems a bit messy.
#10
Old 04-25-2009, 12:32 PM
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With the bettas I've had, I went with the ice water then pop the container in the freezer for awhile method. At least it was quick. I don't have a disposer, so that option is out.

The thought of trying to decapitate a betta is hilarious. Hilariously awful, but hilarious nonetheless. They're way too little to get a good grip on.

Last edited by whiterabbit; 04-25-2009 at 12:33 PM. Reason: Can't type today
#11
Old 04-25-2009, 12:37 PM
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Do you want your last memories of your fishy friend to be of a brief, but incredibly painful death? If not, the clove oil and vodka method is relatively simple and uses readily available products. (Most grocery stores or pharmacies carry clove oil.)

http://wisegeek.com/what-is-the-...ize-a-fish.htm

Also, congratulations on wanting to treat your pet humanly.
#12
Old 04-25-2009, 01:14 PM
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A few quotes from that website, Bolt the Nut:

I just put my fish to sleep. I followed the directions on this site exactly as stated, and the clove oil did not put my fish to sleep. I waited and waited and still nothing, so I added a bit more, and it began to irritate them. They gasped for air at the top, and I could see the skin around their eyes was all red, which it had not been before. My fish looked worse than ever and were apparently suffering worse than ever, and I did not know what to do at this point so I had to kill them in an extremely horrible way - at least to me it was - and I don't even want to explain it to people on this site. I needed to act fast, and your website doesn't tell us what to do when the oil doesn't work, and it's doing damage. I got the exact oil you recommend and double checked it with my vet. I was completely unprepared for this situation, and I feel horrible.


I found this article when I was looking for a humane way to send a group of guppies to their watery heaven. A man gave me a tank full of fish that were just awfully twisted, deformed and sick. I suspect they had tuberculosis, but I suppose it could have been strictly inbreeding. I decided to use the clove oil method and it worked great. The fish slowly fell asleep. No spaz attacks or stress. After about 30 minutes of them being asleep, I added the vodka and their gills stopped moving. It made me feel better knowing that they went peacefully after a life of such pain. Then, I had a plecostomus that I thought had a huge patch of fungus. (It turned out to be Argulus) I used just 1 drop of clove to about 1 pint of water. So, I slowly added a few drops of the mixture. After a few minutes, he started spazing out like crazy. He was literally trying to suck up the sides to get out of the mixture. I figured he was just freaking because he didn't know what was happening. It turns out that it actually killed him a few minutes later. I don't know if armored fish are somehow different, but he completely spazed and died and I was so upset. I felt like I murdered one of my favorite fish. So, tonight I looked at one of my Purple Moscow Guppy babies. He had a tiny hair stuck in his mouth and he couldn't get it out. So, I made the same mixture. 1 drop to about 1 pint. I added a few drops and he slowly fell asleep. I used tweezers and pulled out the hair, it was long and hard to get out. Then, I slowly took out the old water and added some of the tank water. I have been slowly doing this for about 45 minutes. Take out old water, add tank water. He looks dead and pale. But I still see his tiny heart beating. I have no idea how long to wait for him to wake up, but if he doesn't wake up within the next hour, I'm going to euthanize him. I figure 2 hours in clean water and he should be moving. Or id this wrong? Be very careful when using clove oil to put fish to sleep temporarily. It hasn't worked well for me so far!

Well, this method did not work well on our goldfish. I'm really upset as I was trying to find a peaceful method for him and I think I made it way worse than if I would've just chopped his head off. I got 100% clove oil (Humco brand), put one dose in the water, he did not fall asleep and he was really distressed by the clove oil addition. After waiting 10 minutes, he was more relaxed, but still swimming, so I added more clove oil and waited another 10. Now it seemed like he was asleep, his gills weren't even moving, so I poured in the vodka. Then he woke up and started thrashing again. It is horrible. (He is in 16 oz of water and I added 4 oz vodka). He is about 3 inches long, so maybe I needed a higher dose of the clove oil to begin with, but still, the vodka should have done him in by now and his gills are STILL MOVING. Christ. I feel horrible. I don't recommend this method at all. Go and get some finquel. I looked in three pet stores for it and couldn't find it, which makes me sad that the pet stores aren't even euthanizing their fish in a humane way.


etc etc etc

Doesn't sound too good to me!

I am also amazed that there are people this attached to fish. I suppose there's no logical difference between them and other pets, just never come across people who gave two hoots about fish before
#13
Old 04-25-2009, 02:20 PM
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Quote:
Originally Posted by Chief Pedant View Post
I've seen arguments on my fish hobbyist sites against icewater.
What are those? It may not work rapidly enough on cold-water fish, but I would think it should be quick enough on tropicals. But I can't say I have tried it myself.

The fact is, nothing is going to be completely painless or non-traumatic to the fish, unless perhaps you go to the trouble of getting a fish anesthetic that veterinarians use and overdose it. So the quicker you can do the deed the better.
#14
Old 04-25-2009, 02:47 PM
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Drop it into a pot of boiling water. Instant death that is most likely painless.

Then add a bit of white wine, cream, tarragon...
#15
Old 04-25-2009, 02:49 PM
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Originally Posted by Colibri View Post
2. Drop it into alcohol at as high a concentration you can find. (Vodka would work.) Again, this should almost instantly paralyze and kill the fish.
I can help.
#16
Old 04-25-2009, 02:51 PM
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It was time for a water change anyway so I put about a gallon of tank water into the sink with Mr. Sickfisch, turned on the disposal and pulled the plug. Probably very disorienting for the fishy, and maybe painful for a 10th of a second. But certainly better than suffocating in the sewer or carrying on like he was for the next 24-48 hours.

I really don't like watching anything suffer, even the fishes.

Do fish get tuberculosis or was that a joke?
#17
Old 04-25-2009, 02:59 PM
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I don't mind to sound callous - I understand that, from the owner's perspective, this might matter. But is there really any need, from the fish's perspective, to ensure a humane death? Their brains are roughly insect-sized, right? When I squash a mosquito, I don't do it to be cruel - but I don't particularly care whether it suffers, either.
#18
Old 04-25-2009, 03:08 PM
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I think the freezing solution sounds like the bet one.
#19
Old 04-25-2009, 03:15 PM
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Here's a site that discusses euthanasia of fish.

Top contenders with a humane rating of 100%:
  • Drop into hard alcohol like vodka.
  • Drop or bathe in MS-222 (Tricaine Methanesulfonate anesthetic, but use a lethal dose)
  • Electrocution (easy on the fish, not so great for you so don't screw around)
  • Drop into freezing water (for tropicals, not coldwater fish).
  • Drop into boiling water (for coldwater fish, not tropicals).

I'd say the garbage disposal is probably just about as humane, from a quickest is best standpoint.
#20
Old 04-25-2009, 03:57 PM
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Quote:
Originally Posted by Chief Pedant View Post
If it's small, I think the kitchen garbage disposer solves merciful dispatch of life and corpse disposition simultaneously. Fire up the disponser and drop it in.
"WHOOPS! Shredded Sushi." Is anyone else having a Zak McKracken moment here? (Electrocution was an option, too. Still better than what happens to the hamster in Maniac Mansion...)
#21
Old 04-25-2009, 04:44 PM
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(by CP) : "I've seen arguments on my fish hobbyist sites against icewater."

Quote:
Originally Posted by Colibri View Post
What are those? It may not work rapidly enough on cold-water fish, but I would think it should be quick enough on tropicals. But I can't say I have tried it myself.

The fact is, nothing is going to be completely painless or non-traumatic to the fish, unless perhaps you go to the trouble of getting a fish anesthetic that veterinarians use and overdose it. So the quicker you can do the deed the better.
I have tried ice water, freezer, and heaving them out onto the yard when it's around zero F. I wasn't impressed that the icewater or freezer were particularly instantaneous; the yard one was pretty much a goner at the time of disposal. I myself dislike jumping into icewater. I think it hurts, and it is certainly not an instantaneous death. Of course all of this anthropomorphizing has a fair amount of speculation. Here are a couple of equally speculative, potentially unsound, and completely unscientific opinions of the type I was talking about. I myself am probably too calloused to fret over any method, and certainly too cheap to do some sort of anesthetic method. On the other hand, my calloused method of sending them down the disposer is definitely instantaneous and unambiguously discomfort-free. I've been a pretty successful hobbyist with my African Cichlids, so I don't have too much personal experience with putting them down.

From http://wetwebmedia.com/euthanasia.htm

"How to euthanise your fish: Freezing

Burgess et all (1998) do not recommend the use of ice or freezing water to euthanise fish, but Brown (2005) specifically describes a process that is acceptable for very small fish (under 5 cm in length). The fish is either (a) exposed to freezing cold water but is not in contact with the ice itself; or (b) placed in a container of normal temperature water from the tank and then that container is transferred to a freezer where it can cool down to below freezing."



From http://nippyfish.net/euthanasia.html (Oddly, the title has nothing to do with the discussion of the method...)

"Unacceptable Methods for Fish Euthanization:

1. Freezer Method:
Dropping your fish into freezing ice water or putting them in the freezer to slowly freeze (hypothermia method) does not quietly put your fish to sleep. In cold blooded animals, it is believed that the formation of ice crystals in the tissue may create discomfort or severe pain. The hypothermia method is never ok. Rapid freezing may be applied only if the fish is deeply anesthetized prior.
"
#22
Old 04-25-2009, 06:50 PM
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When managing a fish room, anything we needed to euthanize immediately we slammed against a counter top in a net. Instantaneous.

With fish at home, where I was likely to have more time, I used the freezer method. Fish in tank water in plastic bag, to cool down and freeze. The theory being that as the fish's body temperature dropped, their metabolism slowed and their "awareness" decreased, well before the formation of any ice crystals. At least, I never got a complaint. Used the same method with reptiles.
#23
Old 04-25-2009, 06:57 PM
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Originally Posted by levdrakon View Post
[*]Drop into boiling water (for coldwater fish, not tropicals).
OK, I can buy that coldwater fish are resistant to freezing. But tropicals resistant to being boiled? Riiight.
#24
Old 04-25-2009, 07:18 PM
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Quote:
Originally Posted by Bolt the Nut View Post
Do you want your last memories of your fishy friend to be of a brief, but incredibly painful death? If not, the clove oil and vodka method is relatively simple and uses readily available products. (Most grocery stores or pharmacies carry clove oil.)

http://wisegeek.com/what-is-the-...ize-a-fish.htm

Also, congratulations on wanting to treat your pet humanly.
For me, the clove oil method has always worked well. I found clove oil in a toothache remedy medication at the local pharmacy, I put it in a small container with some water, shook it very well to get the clove oil to mix with the water, and then put the fish in the container.
Once the fish is clearly non responsive from the clove oil, *then* I freeze them (because my belief is that freezing could potentially be painful, I would not want to do it while the fish was still aware, but it seems like a good way to ensure the fish won't wake up).

Some people don't sympathize much with fish because they seem so different from humans, but from watching their behavior I am convinced they are capable of suffering when they don't feel well. I feel we owe it to any animal in our care to try to give it the most humane death we can.
#25
Old 04-25-2009, 07:30 PM
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Originally Posted by Cosmic Relief View Post
OK, I can buy that coldwater fish are resistant to freezing. But tropicals resistant to being boiled? Riiight.
I don't buy the reasoning either. Both the quick freezing and quick boiling work because of the sudden shock.

Looks like my earlier link is screwed up. Anyone interested could try again.
#26
Old 04-25-2009, 07:54 PM
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Drop him into my tank with 2 turtles. He would be there for 3 seconds.
#27
Old 04-25-2009, 07:59 PM
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I see lots of recommendation for alcohol such as vodka, but wouldn't rubbing alcohol be a better option both in terms of cost and function? It's a cheaper product with higher concentrations of alcohol.

(Note: I know that some rubbing alcohol is isopropyl rather than ethyl alcohol. I'm not sure if that makes a difference).
#28
Old 04-26-2009, 12:56 AM
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If you use isopropyl alcohol, you'll turn it into a fsh.

Last edited by Tenebras; 04-26-2009 at 12:57 AM.
#29
Old 04-23-2016, 12:29 PM
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Freezing is not recommended

Out of all the "old-school" methods, this process seems most inhumane. The AVMA (American Veterinary Medical Association) does not advocate freezing fish as an acceptable method of euthanasia; the only way they would approve of cooling would be to deep freeze an animal that is already under deep anesthesia.

Decapitation - Swift and Surely

This method is self-explanatory you simply remove the fish from the water and use a sharp knife to chop off its head, thus ending its life. The fish might feel something as you slice the knife in; even it is momentary pain. At least this method is quick (as long as you do not hesitate once you start the task). The AVMA believes that this can be acceptable as long as it is coupled with anesthesia to begin with.

Carbon Dioxide

Carbon dioxide is naturally present in the water your fish live in anyway it is a result of the respiration process. It can also be used as a method to euthanize fish because the addition of carbon dioxide to the water decreases oxygen levels, thus causing your fish to suffocate. Alka Seltzer is a popular source for carbon dioxide to be released in water. This method may seem innocuous enough, but most people who have used this method say that their fish thrashed around a little bit just as if the fish were out of water (here is one person's story). You may need to decapitate or freeze the fish afterwards to ensure death. The AVMA supports this method and many universities advocate using this method as well (see the University of Washington's Policy for Euthanasia for Fish Species). Dr. Craig Harms (http://petplace.com/fish/euthana...ish/page1.aspx) describes this method; 8 tablets of Alka Seltzer is required per gallon of water.
#30
Old 04-23-2016, 12:35 PM
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Burial at sea is the traditional method. There's a transfer system in your bathroom.
#31
Old 04-23-2016, 03:29 PM
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Quote:
Originally Posted by TriPolar View Post
Burial at sea is the traditional method. There's a transfer system in your bathroom.
Despite what Gill said in Finding Nemo, all drains (and toilets) do NOT lead to the ocean.

Instead, all sanitary drains lead either to a wastewater treatment facility (WWTF) or a septic system. The solids at a WWTF end up being incinerated or sent to a landfill.
#32
Old 04-23-2016, 04:22 PM
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How do you dispatch zombie fish?
#33
Old 04-23-2016, 08:54 PM
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I've given some thought to the problem of quickly killing fish, as I do a bit of fishing myself. The common method for medium-sized fish (like perch) around here is to break the neck of the fish. This certainly paralyzes the fish, but does it kill them fast enough? Remember, fish don't breathe like mammals, and are not dependent on nerve impulses to the body to keep the blood oxygenated. It seems to me like breaking the neck would add pain rather than shorten it!
My own preferred method is to stick a knife through the upper part of the eye socket into the brain and give it a couple of twists. Is this good enough, or is there an even better way?
(I guess smashing the head with a hammer would be even faster, but it makes filleting hard...)
#34
Old 04-24-2016, 12:10 AM
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Quote:
I've given some thought to the problem of quickly killing fish, as I do a bit of fishing myself. The common method for medium-sized fish (like perch) around here is to break the neck of the fish.
Fish don't have necks... but I'm assuming you mean a technique of bending and breaking the spinal column near the back of the head?

Quote:
This certainly paralyzes the fish, but does it kill them last enough? Remember, fish don't breathe like mammals, and are not dependent on nerve impulses to the body to keep the blood oxygenated.
Not sure what this means. Fish don't breath air, but they do respire none the less (by passing water over the gills). And yes their respiration system does use nerve impulses and oxygen level sensing to function.

Quote:
Is this good enough, or is there an even betterway?
(I guess smashing the head with a hammer would be even faster, but it makes filleting hard...)
The fish described in the OP 7 years ago was about the size of a large coin, so physical trauma to kill it would certainly work, but you'd essentially just splatter it with a hammer like a ketchup packet. A seemingly more humane way to go would be to use clove oil. But the chasing with net and stress of moving the fish to a little "death chamber" container where you'd give it the happy juice mixed with a bit of water would probably negate the benefit. Yeah, just net a little fish out and smash it with a small blunt object; even step on it - if you can go from tank to dead on the floor/countertop in 5 seconds or less you're good.

For larger angling size fish, use some sort of club to smack the fish on the back of the head. It can be as crude as a piece of wood or plastic pipe, a foot or 2 long will be enough to kill most fish. No need to risk cutting yourself or use precision twisting techniques.
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