Euthanasia Of Freshwater Fish

[OohFeeshy]

I'm just wondering, what is the thinking on speed vs possible suffering caused? There's a whole host of (lesser used) methods that, although potentially high on the suffering scale (well, not exactly- I wouldn't say there's any evidence to say so, but the potential is there) are also very quick.

I think the problem comes when trying to weigh up speed vs ethics of euthanisation technique, and suffering caused during euthanisation vs suffering caused (in the case of disease or deformity) if the action is not taken.

 

[jourdy288]

I believe that fish feel pain, but I also believe you should put a fish down if it's going through intense pain and the condition cannot be cured. If you could sedate the fish, then do something like drop it into boiling water, the nervous system would (A. Be cloudy, the fish doesn't seem to mind, and (B. Already boiling water would cook the nervous system instantaneously. Remember to relax the fish first with sedative, or that could mean more suffering.


Note: In the name of science, a new disease should only be attempted to be cured, the fish not put to sleep. One fishes suffering could save thousands of others.

 

[Aphotic Phoenix]

Already boiling water would cook the nervous system instantaneously.

Can you supply evidence to support your opinion that the rapid, or not so rapid depending on a variety of factors such as mass and body insulation, denaturing of proteins caused by high heat exposure is a more swift and humane form of euthanasia than other methods?

 

[Invader Xan]

If I might interject -- the use of boiling water would probably depend on the size of the fish in question. There would be a steep temperature gradient between the fish's internal temperature and the temperature of the water, so it would quickly cause tissue necrosis at a steady rate from the outside in, killing the fish.

With small fish like, for instance, neons -- the tissues of the entire fish would be killed more or less instantaneously. The larger the fish, the longer it would take to die, and personally I'd construe anything over a couple of seconds to be cruel (though I don't know much about fish nervous systems, so this could vary depending on the fish's reaction speed). Thus, my argument would be -- euthanasia by boiling water would be perfectly humane for small fish, but not for anything larger.

Given that the thermal conductivity of a fish is comparable with that of salt water, it should be possible to calculate an upper size limit on the fish in question.


Incidentally, this is why some large seafood restaurants prefer not to boil lobsters anymore. There's a company (I think it's based somewhere in America) that sells a machine for electrocuting lobsters as a more humane way of killing them prior to cooking.

 

[jourdy288]

The sedation would be good for large fish. Or, a more painless way to die is morphine. I am not a crazy person, but sometimes doctors euthanise people with it. This is the sad truth.

 

[rdd1952]

The sedation would be good for large fish. Or, a more painless way to die is morphine. I am not a crazy person, but sometimes doctors euthanise people with it. This is the sad truth.

Officially it isn't euthanising them but that is the effect it has. Basically, with morphine, they go to sleep and their organs slowly stop functioning. Don't know the whole medical part but once they start giving a patent morphine in the large doses to ease their pain, it's only a matter of time. I'm sure morphine would work on fish but I don't think it is something the average person could get their hands on.

 

[jourdy288]

I think for larger fish sedating them then severing the spinal cord is the best way to go.

 

[nmonks]

Andy,

This is where you lose me. If the guy is publishing on his university web site -- that's not peer review. What matters is whether Rose's critique is reviewed by other scientists in the field before publication, Sneddon's work certainly was. So until Rose publishes his critique, I'm not swayed.

Now, the second issue is that he cites one particular definition. McDonalds cite a Big Mac and Fries as a healthy part of a balanced diet. Doesn't make it true. Again, by publishing *his* definition of pain in a peer-review journal, the scientific community gets to decide whether it's reasonable or not.

In short, James Rose contributes nothing more to the debate any more than my personal opinions do.

Cheers, Neale

James Rose, a fisherman and a professor in the University of Wyoming's Department of Zoology and Physiology, wrote a scathing critique of Sneddon's findings, which appeared on the university Web site, claiming that they contained poor methodology and misinterpreted the data. The key to his objections centered around how animals perceive pain. He cited the Seattle-based International Association for the Study of Pain, which defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage..." And, he said, the signals sent by nociceptors are not in themselves pain.

 

[Bignose]

Neale, Rose's work has been published. See " The Neurobehavioral nature of fishes and the question of awareness and pain" in Reviews in Fisheries Science Vol 10, 2002. It has at least sparked interest, too, since it has been cited 50 times (according to the database I use), that's a pretty good rate since 2002.

 

[Rueon]

This forum interested me quite a bit, as we hate to see fish suffer in the tank and being bullied by the rest when they are dying.

Euthanasia is a very gruesome subject, but to my luck I found an old book in a library sale that gave 3 tips for the "most humane" methods of carrying out this awful act, although the book states there is no perfect way to do this. The book is "A Practical Guide to Keeping Healthy Fish" by Lance Jepson.

1) Overdose the fish with a recognised fish Anaesthetic such as MS222 or Benzocaine.
2) Deliver a quick severe trauma to the back of the skull using an angler's club or mallet for killing fish. This will stun the fish and then decapitation can take place.
3) Alka Seltzer. Place the fish in a minimal amount of water and add as many Alka Seltzer tablets as possible. The CO2 released, the book states, as the tablets fizz and disolve will aneathetise and eventually kill the fish.

The book states that there are 3 methods to be avoided at all costs.
1) Death by Hypothermia usually by placing the fish in the freezer. This applies especially to temperate and cold water fish especially that are designed to endure low temperature.
2) Flushing down the toilet. Out of sight and out of mind, but it will not solve any welfare problems.
3) Never do nothing.

I hope this offers some tips as it is the most disturbing part of fishkeeping watching your fish suffer and what to do.

 

[Tokis-Phoenix]

For me, i've never had to euthanise large fish, the only fish i've ever had to euthanise are fish like neons, guppys, platys and a molly once etc- basically small fish.

I have always found that putting the fish in a freezing bowl of water is a humane form of euthanasia (i.e. fish does not appear to suffer much, and dies very quickly, within seconds) and has always worked with 100% success for me.

This is the way i go about it;

a. Put plastic/ceramic/glass etc bowl with about 2-3inches of water in it in freezer.
b. Allow water to freeze enough to form a thin layer of ice completely covering the surface of the water.
c. Take bowl out of freezer and break the ice on the surface of the water.
d. Net sick fish and put it in bowl of water and watch it and wait for it to die.
e. Remove dead fish and wrap it in tissue paper and then dispose of it (bury it or put it in bin etc).


I've had to ethunise many fish during the years i have been fishkeeping, most of the fish i have had to euthanise were during certain moments in my fishkeeping experience, mostly during when i had a couple of outbreaks of fish tb and NTD (both untreatable and lethal/nasty fish diseases).
I've also had to euthanise fish dying from old age, like my old female molly, when she reached the grand old molly age of just over 4years old (the maximum average life expectancy for mollys), her health went down hill a lot, she gradually stopped eating and being active and ended up getting a swimbladder problem in the last week or so of her life as she lost a lot of body weight. I knew that she wasn't going to get better and her body wasn't coping anymore due to her age, so i euthanised her with the freezing water method when i knew she was in a bad way and was not going to get better. She died very quickly with this method.


So i would say i'm very experienced with the freezing water method of euthanasia on small fish. I've watched small tropical fish die with this method each time i've used it- what happens is that the fish hovers in the water for a few moments, then dashes around once or twice and then dies seconds after that. I watch the fish for fin, mouth and gill movements. Even though i know the fish is dead (its never taken more than about 20 or so seconds tops for fish to die with this method for me, i define "dead" being when the fish is no longer breathing or moving), i leave it in the water for a further minute or so to make sure there is absolutely no chance of the fish revieving.


You are never really going to be able to kill the fish absolutely instantainously, neither can you do the same with human beings. With human beings, i have read stories that when humans have been decapitated, it can take minutes before the brain is well and truly dead.
I think the fish dying in 30 seconds or less with the fish displaying little signs of stress or pain is a sign of a humane death.



The freezing method is always going to work best on small tropical fish. On sub-tropical or coldwater fish, it probably wouldn't work as well, and certainly not on fish larger than 3inches long.
My question, is that what are the most humane methods of euthanisa on large fish (particularly tough ones like large plecos)? I hate to think about anything bad happening to any of my plecos, but what if (imaginary scenario) one of my large plecos contracted an lethal and untreatable and nasty disease and had to be euthanised, what would you people do in such a situation? There are plenty of forms of euthanisia that work very well on small tropical fish, but not that many good methods for large ones.

 

[OohFeeshy]

With bigger fish it seems to be that the more 'brutal' methods are best- hard whack on the head then destroy the brain, for instance. People use clove oil plenty too, but that's up for debate.

 

[jourdy288]

What is NTD? Oh, wait, neon tetra disease.

 

[CallMeJoe]

I recommend (from my very limited experience) the CO2 method via Alka Seltzer. I've needed to use it only twice, and both times the fish expired quickly with no signs of distress.

 

[Hawkins]

I believe the real question here is, as I have heard from Bignose, whether or not fish feel pain and I see no problem with this discussion leaning into that realm.

Dr L Sneddon at the university of liverpool completed a study which she considers to prove fish do feel pain. I don't have the name of the study but it involved rainbow trout and using venom from a bee sting.

[URL="http/www.wellcome.ac.uk/en/pain/microsite/culture2.html"]http/www.wellcome.ac.uk/en/pain/microsite/culture2.html[/URL]

The link has more detail, but I can't find the name of the particular study.

Ok, then, here's a good welcome to the scientific section. Fella, whether the word I bolded (prove) in your quote was your word or Dr. Sneddon's, it is an exceptionally poor choice to use in the scientific section. Unless the fish actually came out of the tank and told Dr. Sneddon that they felt pain, nothing has been proven. Now, correct phrasing here would have been "shows strong evidence that fish feel pain" or "shows that it is likely or very likely that fish feel pain" or something similar. But, no good and honest scientist can claim that research like this proves anything.

But to be fair, if two Betta Splendens have been fighting and one is ripped to shreads, you can see they are in pain