# "Do fish feel pain?" and "How should I kill my fish?"



## AshMashMash (Oct 28, 2007)

Just because I was reading/posting in another thread about pain and euthanasia of reptiles, thought it might be interesting to point out some of the thoughts about these topics in fish. 

*Do fish feel pain?

*The current thinking is that the short answer is: yes. Or at least some sort of nociception - relating nociception to the anthropomorphic emotion "pain" is a difficult one. A research paper _[Pain and Nociception in Reptiles, Craig Mosley, DVM, MSc, DACVA]_ describes it well:



> *Pain *is inherently subjective, and is defined as unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage, noting that the inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment.
> 
> *Nociception *generally refers to the physiologic or neuroanatomical components necessary to sense and transmit the noxious stimuli to the brain where it can ultimately be interpreted as a painful experience (ie, pain).


There is good evidence to show that fish exhibit nociception. I shall take some quotes from this article: 
_
Fish Analgesia: Pain, Stress, Fear Aversion, or Nociception? E. Scott Weber III, VMD, MSc (Distinction) Aquatic Pathobiology/Veterinary Science._

What to look for:



> When monitoring fish patients for clinical signs of distress, some considerations include:
> The subjective assessments of *body orientation and swimming, feeding, hiding, and/or spatial positioning* (near aeration or heater). Additional parameters are more medically specific and objective, for example, environmental quality parameters, *heart rate, opercular or respiratory rate, lethargy, fin clamping *[and]* darkening,*


Evidence for "pain" in fish:



> Several changes in blood chemistry have been observed in largemouth bass (Micropterus salmoides) from tournament - caught fish in a catch-and-release tournament that were sampled within 5 minutes after official tournament weigh-in. *Several chemistry parameters for these animals were significantly greater than controls*, including plasma cortisol, glucose, sodium, and potassium, and large changes in metabolic status for these fish included major reductions in the muscle energy stores phosphocreatine, adenosine triphosphate, and glycogen, and large increases in muscle and plasma lactate concentrations.





> Rainbow trout treated with noxious stimuli injected into their lips can also have unusual behavior such as rocking on either pectoral fin from side to side, and also rubbing their lips into the gravel and against the sides of the tank





> One of the most common subjective reasons for providing pain medication in fish patients is to eliminate anorexia. Inappetence or anorexia is a common finding of compromised fish patients, and can be a complication after anesthesia, after diagnostic procedures, and/or following surgery. There is greater evidence for the stress mechanisms in causing fish to become anorectic. *In rainbow trout chronic plasma cortisol elevation affected individual appetite* with subsequent decreases in growth rate, condition factor, and food conversion efficiency


(cortisol is a steroid which the body releases in times of stress)



> An example of behavioral responses to acute noxious stimuli comparing rainbow trout with goldfish involved observing animals after administering electric shocks of 2 different intensities directly to the skin; *goldfish demonstrated spatially cued shock avoidance* with significantly improved shock-avoidance learning, whereas *trout displayed a difference when a conspecific was presented and remained in the area of the conspecific when it was being subjected to the stimuli*.


i.e. trout like to be near a "friend" when they are in pain.

OK, so fish feel pain? What does that mean for us? I think the main thing that means for us is when it comes time to decide whether a fish is suffering and should be euthanased or not. Fish are _exempt_ from the Veterinary Surgeons Act 1966. This act covers what Veterinary Surgeons _only_ may do. As fish are exempt, it is legal for non-veterinary surgeons to euthanase fish. 

*How should I kill my fish?

*The one place I would send anyone wanting a quick and easy reference to this sort of question is the Merck Veterinary Manual. It covers this issue nicely in one neat box found HERE. 

The acceptable methods are:



> Barbiturates, inhalant anesthetics, CO2, *tricaine methane sulfonate*, benzocaine hydrochloride, 2-phenoxyethanol


Conditionally acceptable methods are:



> Decapitation and pithing, stunning and decapitation/pithing


So which methods are we going to use? The method highlighted in the first quotation is my recommended. Tricaine methane sulfonate also known as MS-222 is an anaesthetic used in in fish and amphibians. It's active component is *eugenol*. 

So, of course, the average person doesn't have MS-222 lying about, but what we can purchase easily and legally is a dental product called "Clove oil". 

*Clove oil* contains eugenol, and has similar effects to MS-222. It can easily be purchased at shops like Boots and chemists, and smells strongly like toothpaste or mouthwash. It can be used at about *10 drops per gallon of water *in a bucket of tank water that the fish came from at the same temperature. The solution is not incredibly water soluble, so should be put into a bottle and shaken vigorously first to emulsify it, then added slowly into the container with the fish. The fish will go to the bottom and pass away. Once the fish has not moved 5 minutes, it should be placed into _fresh_ tank water for 30 mins and should of course remain dead.

Conditionally acceptable methods do include decapitation and pithing of the brain. If you feel comfortable with this method and are sure of a swift kill, this is also acceptable. It is, of course, easier in larger fish than smaller. 

Lastly, it is widely recognised that fish do feel pain in response to hypothermia - cooling. The nerves do _not_ slow down as previously thought, and actually freezing/cooling is _not_ acceptable for either analgesia, anaesthesia or euthanasia.* Freezing is not a humane way to kill fish!*

Hope that was interesting!


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## hippyhaplos (Jan 12, 2010)

Clove oil will always be the way for me... pithing, decapitation etc just isn't something I could do.

I remember extracting eugenol from cloves in first year at uni... still have it somewhere


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## goldie1212 (Mar 5, 2010)

same here, clove oil for me. i couldnt and wouldnt do it any other way.


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## AshMashMash (Oct 28, 2007)

hippyhaplos said:


> Clove oil will always be the way for me... pithing, decapitation etc just isn't something I could do.
> 
> I remember extracting eugenol from cloves in first year at uni... still have it somewhere





goldie1212 said:


> same here, clove oil for me. i couldnt and wouldnt do it any other way.


Good good guys :2thumb:


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## Marinam2 (Sep 4, 2007)

A good solid bang to the head took mine out quickly!


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## chrismc91 (Jan 31, 2011)

Marinam2 said:


> A good solid bang to the head took mine out quickly!


 
Same here,i personally don't think fish feel pain(angler for 20 years and koi keeper for 5).They get stressed and thats about it imho!


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## AshMashMash (Oct 28, 2007)

Marinam2 said:


> A good solid bang to the head took mine out quickly!


Definitely fair enough  Might be hard with a neon though :lol2:



chrismc91 said:


> Same here,i personally don't think fish feel pain(angler for 20 years and koi keeper for 5).They get stressed and thats about it imho!


You're wrong. Did you read my post?


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## Devi (Jan 9, 2011)

Just a question -
Why are you posting how to kill fish? Surely the average keeper should not be killing their fish without veterinary input? I see the use in some fields, but as a general keeping forum I feel this could be misused.


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## AshMashMash (Oct 28, 2007)

Devi said:


> Just a question -
> Why are you posting how to kill fish? Surely the average keeper should not be killing their fish without veterinary input? I see the use in some fields, but as a general keeping forum I feel this could be misused.


See below:



AshMashMash said:


> Fish are _exempt_ from the Veterinary Surgeons Act 1966. This act covers what Veterinary Surgeons _only_ may do. As fish are exempt, it is legal for non-veterinary surgeons to euthanase fish.


Also I think using the methods I described with eugenol is very humane - you can't really go wrong. If you were to take it to a vets, most wouldn't even have MS-222. If they did, they'd use that, which is the same as clove oil.


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## Devi (Jan 9, 2011)

I'm not debating the necessity at all. All animals will need euthanasia, through serious illness or deformity. I'm just wondering if the post could use a disclaimer, something along the lines of not killing your fish because you've become bored of it, the kids aren't bothered, or you fancy a break. Just a few reasons I've heard from people who flush their goldfish (possibly the worst method of euthanasia).


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## chrismc91 (Jan 31, 2011)

AshMashMash said:


> Definitely fair enough  Might be hard with a neon though :lol2:
> 
> 
> 
> You're wrong. Did you read my post?


 
Yes i did and found it very informative (read it about trout befor),but I've also read that they don't feel pain ,many times before.They get stressed IMHO witch causes a reaction .If they felt pain why would they take a anglers bate come of the hook then take the bait again?Or If they ware caught put in a keep net then continue to eat inside the keep net?Not a sign of a fish in pain to me.Jut cause you have quoted a few lines doesn't make you right!As for trout not growing dew to pain most record trout/fish get caught on a very occasionally bases so as for stumping growth that doesn't make sense?


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## hippyhaplos (Jan 12, 2010)

More and more research is being done in this field, and it is accepted that fish feel pain.

The carp don't associate food with being caught... if they'd never feed. If a fish gets caught once, it won't associate food with being caught, as there are probably thousands of times that fish has fed without being caught.


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## chrismc91 (Jan 31, 2011)

hippyhaplos said:


> More and more research is being done in this field, and it is accepted that fish feel pain.
> 
> The carp don't associate food with being caught... if they'd never feed. If a fish gets caught once, it won't associate food with being caught, as there are probably thousands of times that fish has fed without being caught.


 
am not on about carp(scavengers) ,but more wild fish like barbel(sin to put in a keep net but it does happen),chub,grayling ,tench , etc.

As for a fish not associateteing food with been caufght i don't beleave that ither as a water with high preasure on it ,the fish get wise to baits and become harder to catch unless over stocked like man made fisherys!Hence why anglers have to change tactics/baits.

p.s
I used to think fish felt pain when younger but after so many years of careing/looking after there "natural enviroment" spending many hrs studying there behavioure and variouse nettings of lakes/fish caught i beg to differ!


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## goldie1212 (Mar 5, 2010)

i side with the idea that all living creatures feel pain, that way, even ones that may not feel pain are still treated with the same care and concern as ones known to feel pain. i think fish feel pain personally, and i would never intentionally cause pain to anything. i have however had to euthanise fish before, the last one being a fancy goldfish i took on for someone, which ended up with such bad bouyancy problems she floated upside down with her stomach out of the water, this would have been an awful and drawn out way to die. knowing a humane way to euthanise a sick/dying fish is extremely important IMO. i dont have it in me to fish it out, hold it and bash it on the head, i would worry i didnt do it hard enough or that it would make a disgusting mess if i did it too hard :gasp: so clove oil is the only way for me.


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## LiamRatSnake (Jul 3, 2007)

I've killed a few fish in various ways. For smaller fish I've used clove oil, but anything larger than a neon I bash them over the head or cut through their skull with a knife. I would find it more difficult to do it to one of my goldfish as they're more like pets than the tropical fish.


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## HerpvetUK (Aug 24, 2009)

AshMashMash said:


> See below:
> 
> 
> 
> Also I think using the methods I described with eugenol is very humane - you can't really go wrong. If you were to take it to a vets, most wouldn't even have MS-222. If they did, they'd use that, which is the same as clove oil.


Hello,

Being pedantic, I would just like to point out here that, while both are probably acceptable as fish anaesthetics in practice, MS 222 (tricaine methane sulphonate) is NOT the same as eugenol, and acts differently.

I totally agree that treating fish as is they can feel pain is the only reasonable approach, of course.

Hope this helps,

Bruce.


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## AshMashMash (Oct 28, 2007)

HerpvetUK said:


> Hello,
> 
> Being pedantic, I would just like to point out here that, while both are probably acceptable as fish anaesthetics in practice, MS 222 (tricaine methane sulphonate) is NOT the same as eugenol, and acts differently.
> 
> ...


Yeh, sorry, I didn't mean to say they are the _same_ thing, but contain similar active ingredients - MS 222 contains a eugenol-like compound, no?


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## EquineArcher (Feb 13, 2010)

Very interesting read. :no1:

I've read both sides of the argument, and I do believe that fish that can feel pain, but looking at it from an evolutionary point of view, surely *not* being able to feel pain would be a rather large disadvantage in terms of your fitness?

The pain reaction is designed to prevent harm to an animal, and to teach animals how to avoid damage altogether. Returning to a baited hook several times, in my opinion, does not indicate that fish can't feel pain, merely that their long term memory and intelligence are not hugely advanced.


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## caribe (Mar 21, 2010)

I use clove oil for smaller fish and bash the big ones.

Only If I REALLY need to as I dont like doing it.

I used to use very small quantities of clove oil when transporting big pacu etc in boxes to keep them a bit more quiet before slowly introducing fresh water through a pump.


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## chrismc91 (Jan 31, 2011)

SexyBear77 said:


> Very interesting read. :no1:
> 
> I've read both sides of the argument, and I do believe that fish that can feel pain, but looking at it from an evolutionary point of view, surely *not* being able to feel pain would be a rather large disadvantage in terms of your fitness?
> 
> The pain reaction is designed to prevent harm to an animal, and to teach animals how to avoid damage altogether. Returning to a baited hook several times, in my opinion, does not indicate that fish can't feel pain, merely that their long term memory and intelligence are not hugely advanced.


Disagree i think fish have a ok memory ,from a anglers point of view once fish get used to say sweet corn they no longer take it willy nilly.Fish diguise cerian baits to distress .Here is ware i think there is a fine line between stress and pain.


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## hippyhaplos (Jan 12, 2010)

SexyBear77 said:


> Returning to a baited hook several times, in my opinion, does not indicate that fish can't feel pain, merely that their long term memory and intelligence are not hugely advanced.


Or it could even be that food for bottom feeders can be quite hard to come by, so if they didn't take it when it was available then they'd starve. It's dark at the bottom of lakes/ponds, so how does a fish know it's not the same bit of food? 


chrismc91 said:


> Disagree i think fish have a ok memory ,from a anglers point of view once fish get used to say sweet corn they no longer take it willy nilly.Fish diguise cerian baits to distress .Here is ware i think there is a fine line between stress and pain.


?


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## chrismc91 (Jan 31, 2011)

hippyhaplos said:


> Or it could even be that food for bottom feeders can be quite hard to come by, so if they didn't take it when it was available then they'd starve. It's dark at the bottom of lakes/ponds, so how does a fish know it's not the same bit of food?
> 
> 
> ?


Smel for a start.(watch korda underwater vidios) u will c certian baits/set ups fish get used to!!


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