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Thread: Do Fish Feel Pain?

  1. #11
    Banned adi chicago's Avatar
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    Chronic pain is defined as pain that persists longer than the temporal course of natural healing, associated with a particular type of injury or disease process.[1]
    The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."[2] It is important to note that pain is subjective in nature and is defined by the person experiencing it, and the medical community's understanding of chronic pain now includes the impact that the mind has in processing and interpreting pain signals.
    http://en.wikipedia.org/wiki/Chronic_pain
    DO FISH FEEL PAIN?

    This is not an easy question to answer. Reasonable arguments have been made both to support and refute the claim that fish are capable of sensing and experiencing pain. Summaries of two such arguments follow.

    The Case Against the Experience of Pain in the Fish
    James Rose of the University of Wyoming has put forth a strong argument for the inability of fish to experience pain that relies on analogy between human and fish neuroanatomy. Rose emphasizes the distinction between reaction to injury and psychological experience of pain and emphasizes that the existence of the former does not evince the existence of the latter. Indeed, human experiments have proven that pain is experienced in the brain and that sensation of and reaction to noxious, or potentially harmful, stimuli can occur without the experience of pain. The concept of nociception makes this possible.
    http://www.link.vet.ed.ac.uk/animalwelfare/Fish%20pain/Pain.htm

    The Brain:
    According to Bermond (1997) the highly developed neocortex of the human cerebral hemispheres is responsible for our ability to experience emotions and sensations such as pain. The existence of this feature in the fish brain would strengthen an argument for the ability of fish to experience pain. However, the fish brain is dominated by brainstem components and features very primitive cerebral hemispheres that lack neocortex. Humans require this neocortex for basic sensory functions as it is thought to be responsible for interpreting the sensory information received and processed by our brainstem and spinal cord. In fish, a higher level of cortical sensory interpretation appears nonexistent, since fish behaviour is unaffected by cortical damage. For example, cortical damage in a human may cause blindness whereas the complete removal of a fish’s cerebral hemispheres causes no apparent change in sensory-dependant behaviour.
    If we assume, as Rose and Bermond do, that the neocortex is necessary for pain sensation, then we must admit that sensation of pain in any animal lacking an analogous structure is unlikely. Fish would therefore lack the neurological capability to experience the negative psychological sensation of pain.
    Last edited by adi chicago; 11-06-2008 at 03:12 PM.
    • Dum spiro, spero.
      • Translation: "As long as I breathe, I hope."

  2. #12
    Quote Originally Posted by Sasyrose2 View Post
    OJ, I've been told the most humane way to euthanize a fish, is to freeze them.
    That is what I used to believe. I tried it once on a sick fish and it completely traumatized me. Afterwards I spoke to a vet and he said told me he didn't believe freezing was humane unless the fish was heavily anesthetized first and even then he had doubts. He recommended that I use a fish anesthetic called Finquel, doubling the regular dose that would be used to anesthetize a given fish, and that would provide the most humane death. I have since done it this way several times and never had a problem. Well except that emotionally I find it is a very tough thing to do. It does seem the most human way to me as the fish simply loose consciousness and then their hearts stop. I guess freezing does that too but I could never do that again and believe it doesn't cause the fish a lot of stress, even if momentarily.

  3. #13
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    I do believe that fish feel pain, as much as we might like to believe otherwise when looking at a golden brown fisherman's platter. I gave up all red meat about 15 years ago because I could no longer play the games of calling a pig pork or a cow a hamburger. I still eat fish occasionally though, and right now I am feeling a bit guilty for doing so.

  4. #14

    Wink

    Quote Originally Posted by Sasyrose2 View Post
    I think, at the very least, fish must feel itching. When fish have a parasite, fungus or bacterial infection, they do something they call "flashing", which is just rubbing up against rocks or gravel. This isn't something they normally do. Unfortunately, I've seen fish that look like they have scratched themselves to death.

    OJ, I've been told the most humane way to euthanize a fish, is to freeze them.

    Personally, being involved with koi and a KOI CLUB, I think Nishikigoi should have been given the name MYKISS. They are much prettier than rainbow trout by far, even the ugly ones. Not to mention the prices that are paid for some of these fish. Maybe they should be called MYLOVE.

    Attachment 26140
    How wonderful that you are involved with a koi and a KOI CLUB! Perhaps Nishikigoi should be named mydear. I was just at a Samurai's house called Nomura-san's House in Kanazawa (Japan). They have these monstrous koi's that must be 30-40 lb, perhaps 2.5 feet long, and 6-inches in diameter, lazing in the pond. Nishiki means "brocaded" and koi means carp. I am reminded of the huge carps that are in the imperial moat in Tokyo. As kids, we use to toss mikan (tangerine) slices to them.

    Yes, there is no question that fish will rub themselves when they have parasites. As humans, we don't know all the various means by which fish communicate pain. Fish do exhibit several features of intelligence, however. For example, fish are playful and curious. They can learn and some are adept at recognizing people.

    When I was at the University of Iowa, my room-mate (a medical student) had a piranha that he kept inside huge glass bottle (the kind of glass bottle that is used to hold water for dispensing water). Every day or two, he would feed it goldfish. The piranha eventually grew so big that it cannot be taken out of the bottle without breaking it. When it ate, it would take a bite of the caudal end of the fish and leave just the head bobbing, with fins still moving and eyes moving. The piranha seemed deliberately cruel.

    Several years ago, I was on a radio show in Seattle, Washington. There was some conservative radio show host and I was the token scientist debating a token PETA representative, with people calling in. One of the callers asked whether fish could feel pain and whether we are being cruel to them when we fish. The radio show host gave the PETA representative first shot at the question and she of course said yes. I said that I wasn't sure but that we should give them the benefit of the doubt and treat them as if they feel pain. I am not sure that this was what the radio show host wanted to hear. In any case, he then asked the PETA representative what she would do if she found a mouse in her home. She said that she would carefully trap it and move it out doors. Then he asked her what she would do if she were driving along and there were flies. She said that she would slow down to avoid splattering them on her windshield. Finally, he asked her what she would do if she were on an island with cannibals and they had the choice of her or a cow to eat. She said in a quavering voice that she would run as fast and far as she could. Poor woman.

    I did my PhD thesis on skates (Raja erinacea) and discovered spreading depression in elasmobranch cerebellum. To do that, I had to record from the brains of skates. I cooled them down by running aerated 5˚C seawater through their spiracles, used a sharp scalpel to cut into their cranial cavities (they have collagenous skulls), and then inserted microelectrodes into their cerebellums. They were only lightly restrained. I monitored their heart rate to ascertain if they were getting excited or having pain. It interesting that when I stimulated their cerebellum, their heart rate increased and when I created spreading depression in the cerebellum, their heart rates would slow down as neural activity declined. At least under those conditions, I don't think that I was causing them pain.

    It is very hard to tell if fish have pain. I do know that they will avoid noxious stimuli by swimming way. They will rub parts of themselves raw if there are parasites. They will thrash around if they are scared or excited. However, like many animals, when they are severely injured, they often calm down. A postdoctoral fellow of mine once called this calming down effect a "ninja" state. I asked her what she meant. She said, it is what ninjas do when they are hurt, so that they don't attract attention to themselves. So, I am not sure that motor activity is necessarily reliable for assessing whether a fish is having pain. Monitoring heart rate is much better, in my opinion.

    Finally, regarding how to kill fish... freezing them is one way. However, institutional animal use and care committees usually recommend using a fish anesthetic agent called MS222. Formerly made by Sandoz, this drug is dissolved into water and will rapidly anesthetize a fish placed into the water. After anesthetizing the fish, it can easily be frozen. For example, you can have a plastic bag, fill part of it up with water, add the MS222, and then place the fish into the bag to anesthetize it.

    What people should not do are:
    • Do not flush the living fish down the toilet. Whether a fish can or cannot feel pain, it is a nasty way to die (Source)
    • Do not put unwanted fish into a local pond or river. The fish may not be endemic to the place and certainly may suffer from exposure, lack of food, and being eaten. More important, if it survives and procreates, it may be bad for the environment.

    What you can do if the fish is healthy:
    • Donate them to your local pet store. Sometimes they take them and other people will adopt the fish.
    • Ask your friends whether they want to adopt them. Surprising numbers of people will take your fish.
    • Take them to your office where you can start an aquarium.

    What you can do if the fish is unhealthy:
    • Put the fish on ice and freeze them.
    • If you have access to MS222, anesthetize them first, and then freeze.

    Wise.

    Last edited by Wise Young; 11-06-2008 at 05:04 PM.

  5. #15
    Senior Member Timaru's Avatar
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    Quote Dr. Young: I do know that they will avoid noxious stimuli by swimming way (sic).

    Having been a fisherman since I was old enough to hold a rod I cannot agree with this.

    In order to avoid noxious stimuli (pain) a fish would swim toward the angler to lessen the "pain" however when hooked a fish swims away from the angler increasing pressure on the hook hold thereby increasing the "pain".

    I believe a fish fights because it's being pulled off course, ie. it wants to swim in a straight line but the angler is pulling it to the left, the fish then pulls hard to the right to regain it's original bearing, this continues until it either escapes or is on the bank.

  6. #16
    Quote Originally Posted by Wise Young View Post
    What you can do if the fish is unhealthy:
    • Put the fish on ice and freeze them.
    • If you have access to MS222, anesthetize them first, and then freeze.

    Wise.
    MS222 is sold commercially in pet stores as Finquil (the chemical I mentioned in my post) but I don't believe it is necessary to freeze the fish after administering it. If the dose is high enough and the fish is left in the water containing it for a sufficient time, my experience has been that is enough to kill the fish. Humanely and without undue stress on the fish.

    Freezing a fish isn't pretty and I am not convinced they feel nothing as they freeze to death. But that is just my opinion based on what I have observed with my own fish.

  7. #17
    Quote Originally Posted by orangejello View Post
    MS222 is sold commercially in pet stores as Finquil (the chemical I mentioned in my post) but I don't believe it is necessary to freeze the fish after administering it. If the dose is high enough and the fish is left in the water containing it for a sufficient time, my experience has been that is enough to kill the fish. Humanely and without undue stress on the fish.

    Freezing a fish isn't pretty and I am not convinced they feel nothing as they freeze to death. But that is just my opinion based on what I have observed with my own fish.
    OJ, thank you for giving the commercial name of MS222. I am glad that it is available to the public. When the fish is anesthetized and then frozen, it feels nothing when it is frozen. Rather than waiting for the fish to die of anesthetic overdose, one can put the anesthetized fish into a freezer and the death results from the freezing. However, if one cannot get the anesthestic agent, putting the fish on ice and putting it in a freezer is better than cutting its head off or flushing it down the toilet.

    Wise.

  8. #18
    Quote Originally Posted by Timaru View Post
    Quote Dr. Young: I do know that they will avoid noxious stimuli by swimming way (sic).

    Having been a fisherman since I was old enough to hold a rod I cannot agree with this.

    In order to avoid noxious stimuli (pain) a fish would swim toward the angler to lessen the "pain" however when hooked a fish swims away from the angler increasing pressure on the hook hold thereby increasing the "pain".

    I believe a fish fights because it's being pulled off course, ie. it wants to swim in a straight line but the angler is pulling it to the left, the fish then pulls hard to the right to regain it's original bearing, this continues until it either escapes or is on the bank.
    Now Timaru if a giant someone threw a giant hook at you and it stuck would you really run toward them?

  9. #19
    Quote Originally Posted by Timaru View Post
    Quote Dr. Young: I do know that they will avoid noxious stimuli by swimming way (sic).

    Having been a fisherman since I was old enough to hold a rod I cannot agree with this.

    In order to avoid noxious stimuli (pain) a fish would swim toward the angler to lessen the "pain" however when hooked a fish swims away from the angler increasing pressure on the hook hold thereby increasing the "pain".

    I believe a fish fights because it's being pulled off course, ie. it wants to swim in a straight line but the angler is pulling it to the left, the fish then pulls hard to the right to regain it's original bearing, this continues until it either escapes or is on the bank.
    I was referring to noxious stimulation such as poking a fish on the side. In high school, I spent my summers on an island south of Tokyo called Miyake-jima. I did skin-diving and have speared many fish for dinner. They will swim away when you try to spear them and graze them.

    I don't know what motivates a fish to swim towards or away from a fisherman when it has been hooked. Probably, it is just swimming to get away and sometimes this may be towards and other times it is away from the fisherman. As I said, I don't know whether what the fish is feeling.

    Wise.

  10. #20
    Banned adi chicago's Avatar
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    I feel sorry for the fish ....I was hungry.
    • Dum spiro, spero.
      • Translation: "As long as I breathe, I hope."

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