Do fish feel pain?

[Luiz Rocha]

A new paper just came out on the prestigious journal Fish and Fisheries that promises to reignite the debate.

J D Rose, R Arlinghaus, S J Cooke, B K Diggles, W Sawynok, E D Stevens & C D L Wynne. 2013. Can fish really feel pain? Fish and Fisheries 2013, 1-37.

Here is the abstract:

We review studies claiming that fish feel pain and find deficiencies in the methods used for pain identification, particularly for distinguishing unconscious detection of injurious stimuli (nociception) from conscious pain. Results were also frequently mis- interpreted and not replicable, so claims that fish feel pain remain unsubstantiated. Comparable problems exist in studies of invertebrates. In contrast, an extensive litera- ture involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery. C fiber nociceptors, the most prevalent type in mammals and responsible for excruciating pain in humans, are rare in teleosts and absent in elas- mobranchs studied to date. A-delta nociceptors, not yet found in elasmobranchs, but relatively common in teleosts, likely serve rapid, less noxious injury signaling, trigger- ing escape and avoidance responses. Clearly, fishes have survived well without the full range of nociception typical of humans or other mammals, a circumstance according well with the absence of the specialized cortical regions necessary for pain in humans. We evaluate recent claims for consciousness in fishes, but find these claims lack adequate supporting evidence, neurological feasibility, or the likelihood that consciousness would be adaptive. Even if fishes were conscious, it is unwar- ranted to assume that they possess a human-like capacity for pain. Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain.

 

[KafudaFish]

Saw a blip about that but hadn't had the time to read it. Thank you for the reference.

 

[humaguy]

Thanks Luiz...
On a related note, while taking into consideration the above, can you recommend the most efficient way to euthanize a fish...there is a thread about this and though I do not have the need to do this, I may one day...
I do not embrace the meat clever method..
Some mention the water in a freeze method, water and vodka in a freezer, just vodka, lol...and oil of clove...
Thoughts?
Many thanks and good to see you again in here...

 

[PMc]

As a veterinarian, this is something that we struggle with. I am only a small animal (dogs and cats) guy, but it can be really difficult to recognize every variation of pain even in them. We usually assume, for our patients, that they feel everything you ad I would feel and try to treat appropriately with NSAIDS, Opiates, etc. We certainly think they also suffer anxiety, depression, and a variety of emotions that we would all experience. But it is difficult to know for sure and you have to be careful how you interpret the signs. Some Basset Hounds look like they never had a happy day in their lives but only because we interpret facial expressions the same way we would interpret human expression. In fact, I think dogs can feel emotions more keenly than humans do because they seem to lack some of the inhibitory side of the neural system that humans have. Do they feel pain more keenly? It sure doesn't seem so. This article suggests that fish don't feel pain because they lack the receptors that key pain in us. Their neural systems are simpler than ours and I don't think they suffer anxiety. There would be an obvious evolutionary advantage to registering a painful or unpleasant sensation to trigger a defensive response. I would think that an emotion like joy or anxiety would be a distinct disadvantage. Joy might make you exhibit behaviour that was otherwise inappropriate (turning backflips is an invitation to being eaten). An anxious fish would never leave his hiding hole to feed or mate. Overall, I think this article is saying that they do not experience pain they way we do but they obviously register painful or noxious stimuli. They probably have no capacity to associate an emotion with pain the way we do. Just mental ramblings.

Mc

 

[syrinx]

Fish, as well as all animals feel pain in one form or another. However pain in fish and such is not tied to an emotional response, more a survival response. I am reminded of a old joke about dentists- "Thats not pain your feeling, simply the pressure of my drill on an exposed nerve". Looking at things this way, and removing the emotional human component- pain is a stimulus to cause a reaction to protect the animal for damage.

 

[syrinx]

Fish, as well as all animals feel pain in one form or another. However pain in fish and such is not tied to an emotional response, more a survival response. I am reminded of a old joke about dentists- "Thats not pain your feeling, simply the pressure of my drill on an exposed nerve". Looking at things this way, and removing the emotional human component- pain is a stimulus to cause a reaction to protect the animal for damage.

 

[Fishbulb2]

Fish, as well as all animals feel pain in one form or another. However pain in fish and such is not tied to an emotional response, more a survival response. I am reminded of a old joke about dentists- "Thats not pain your feeling, simply the pressure of my drill on an exposed nerve". Looking at things this way, and removing the emotional human component- pain is a stimulus to cause a reaction to protect the animal for damage.

Very nicely put. I like the quote. As a neuroscientist, we typically refer to these receptors and the responses that their activation evokes as nociceptors and nociceptive response. We study nociception in flies, nematodes, leeches, and anything else you can think of. These are great model systems for studying things like transduction and channels because these preparations are often easier to genetically perturb. But pain, well we try not to use that. That's assigning a fairly high level cognitive process to something we don't really understand well enough. I am looking forward to zebrafish genetics and the exciting neuroscience being done there to trace nociceptive and mechanosensory pathways through the fish brain. I can promise you this, we will learn more in the next ten years regarding fish neurobiology and the brain than we probably did in the last fifty.

Also, regardless whether or not fish feel pain, do what you have to do to put them under when the time comes, but at least try to minimize their nociceptive responses.

FB

 

[humaguy]

Thanks for the excellent info and hypotheses in this thread...

 

[billsreef]

Thanks Luiz! I'm going to have try to remember to pull up the whole paper next week when I expect to have a little breathing room at work. Could be useful in my dealings with our IACUC committee here...they are sadly (and typically) lacking in people that know anything about fish.

 

[Paul B]

I myself do not think fish feel pain. I know they feel something and would not be able to live long if they didn't but a fish is an animal that in almost 100% of the time, is eaten alive and never is allowed to die of old age. An animal such as that would be much beter off if it did not develop a sense of pain.
Also from spending hundreds of hours underwater with them and watching them as they get eaten and seeing how they reacy when they are injured, I have to say that I really don't think they feel anything resembling pain.
A few examples are I once had a hippo tang that got his mouth completely ripped off by a triggerfish. The tang just kept trying to eat like nothing had happened and eventually died but I would think it should at least have hid for a while.
Also while fishing for flounders how many times would you release a small flounder with severe injuries to it's mouth from a hook, and catch it a few minutes later.
One more, I have seen a shark with it's guts ripped out from another, larger shark. He just jept swimming around eating it's own intestines.
I know this doesn't prove anything but it does "imply" at least they fish don't feel the same sensations we refer to as pain.

 

[KafudaFish]

^ I thought of something similar Paul and I was going to ask the question:

If they do feel pain do fish show it?

If you are prey it doesn't make sense to show it.

I am sure PMC has been examining an animal only to touch a wound and the owner act suprised when the animal reacted.

 

[Paul B]

It is something to think about, also if they do feel pain, did all the mysis I fed to my fish over the years feel pain, how about the brine shrimp I hatch or the halibut I had for dinner last night or the clams I feed to my fish.
I hope not. But I don't think we will ever know.

 

[Luiz Rocha]

Thanks Luiz...
On a related note, while taking into consideration the above, can you recommend the most efficient way to euthanize a fish...there is a thread about this and though I do not have the need to do this, I may one day...
I do not embrace the meat clever method..
Some mention the water in a freeze method, water and vodka in a freezer, just vodka, lol...and oil of clove...
Thoughts?
Many thanks and good to see you again in here...

Hey, euthanizing, so that is a delicate question. I am an ichthyologist by training, so having dissected many fish I know exactly where the brain is and go straight for it for a quick death (usually with a pair of scissors). But I understand that most people won't know where the brain is and just keep poking the head of the fish.

So, to avoid prolonged suffering (and for those who are not comfortable with the above), I would do a combination of the methods you mention above. Clove oil alone will not kill the fish, unless it is very high concentration, but freezing will, except that freezing takes a long time if not "aided", so what I would do would be to put the fish in a bag with clove oil and toss that into the freezer. It will die a happy death and won't "feel" cold .

 

[Luiz Rocha]

Thanks Luiz! I'm going to have try to remember to pull up the whole paper next week when I expect to have a little breathing room at work. Could be useful in my dealings with our IACUC committee here...they are sadly (and typically) lacking in people that know anything about fish.

Here is a link to the paper Bill (I forgot to include it in the OP):

http://onlinelibrary.wiley.com/doi/10.1111/faf.12010/abstract

 

[billsreef]

Thanks Luiz. I expect it will come in handy when I start working on some new SOP's for our wet lab facilities

 

[mperales]

In reading the abstract, I think the authors are mainly finding that the studies/methods claiming that fish feel pain are deficient and that they could not substantiate that fish feel pain based on those studies. I'm also a Veterinarian and I agree with my colleague that we are taught to treat any animal as if it feels pain. I feel the authors are inferring that fish don't feel pain due to "extensive literature involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery". I can attest , as my colleague may also, that I have seen animals devour food after a major, painful surgery, and this was before pain control was a standard of care in veterinary medicine. So I don't feel that eating is a fair assesment of feeling / not feeling pain.
When I was in vet school, 23 years ago, I took and elective fish medicine class. Even back then I was taught about fish anesthesia. There are many articles describing anesthetic protocols for fish. Why would this be necessary if fish don't feel pain? I agree that all animals don't acknowledge the degree of pain or are affected by it as we humans are, but I think it does induce some sort of stress in their systems. (stray currents anyone?)

Clove Oil works mainly as an anesthetic. The active ingredient is Eugenol and it causes analgesia at low doses but at higher doses it can cause respiratory suppression leading to death. Problem is Eugenol is not very water soluble, so I recommend mixing it with Ethanol first ( good ol' PGA, or Vodka) before adding it to water. Then putting the mixture plus fish into the freezer.

 

[vitz]

can anyone here please define exactly what they mean by the terms 'feel' and 'pain' ?

i'll wager it's not that simple a task

fwiw-i'm of the opinion that fish do not 'feel' 'pain' in any way remotely similar to how we perceive/'feel' 'pain'

avoiding or reacting to a physical injury stimulus does not necessarily indicate or prove 'feel' reaction to 'pain', or some type of mental/psychological unpleasantness. it's perfectly possible that avoidance behavior to injurious stimuli is nothing more than a well programmed instinctive survival reaction.

an amoeba will react to 'unpleasant' stimuli by avoidance behavior, i'm positive it's not doing so because it 'feels' 'pain'

us humans still don't know how to qualify/quantify pain precisely even for ourselves. most 'pain' evaluations are subjective to/from the one experiencing the pain-otherwise why do pain management doctors who specialize in this sort of thing always ask the patient to describe their pain on an arbitrary subjective pain scale? ('rate your pain on a scale of 1-10')

 

[vitz]

Fish, as well as all animals feel pain in one form or another. However pain in fish and such is not tied to an emotional response, more a survival response. I am reminded of a old joke about dentists- "Thats not pain your feeling, simply the pressure of my drill on an exposed nerve". Looking at things this way, and removing the emotional human component- pain is a stimulus to cause a reaction to protect the animal for damage.

do you have any objective evidence or links to back up that assertion?

do ants feel pain? how do you know?

 

[vitz]

A new paper just came out on the prestigious journal Fish and Fisheries that promises to reignite the debate.

J D Rose, R Arlinghaus, S J Cooke, B K Diggles, W Sawynok, E D Stevens & C D L Wynne. 2013. Can fish really feel pain? Fish and Fisheries 2013, 1-37.

Here is the abstract:

We review studies claiming that fish feel pain and find deficiencies in the methods used for pain identification, particularly for distinguishing unconscious detection of injurious stimuli (nociception) from conscious pain. Results were also frequently mis- interpreted and not replicable, so claims that fish feel pain remain unsubstantiated. Comparable problems exist in studies of invertebrates. In contrast, an extensive litera- ture involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery. C fiber nociceptors, the most prevalent type in mammals and responsible for excruciating pain in humans, are rare in teleosts and absent in elas- mobranchs studied to date. A-delta nociceptors, not yet found in elasmobranchs, but relatively common in teleosts, likely serve rapid, less noxious injury signaling, trigger- ing escape and avoidance responses. Clearly, fishes have survived well without the full range of nociception typical of humans or other mammals, a circumstance according well with the absence of the specialized cortical regions necessary for pain in humans. We evaluate recent claims for consciousness in fishes, but find these claims lack adequate supporting evidence, neurological feasibility, or the likelihood that consciousness would be adaptive. Even if fishes were conscious, it is unwar- ranted to assume that they possess a human-like capacity for pain. Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain.

 

[billsreef]

Perhaps the real question for research should be why would other animals "feel" or "perceive" pain any differently than the human animal? If some "superior" alien species came along and asked themselves if Humans could feel pain, would they think any differently about the question than we do of other animals?

There are times I can't help but wonder if fish I've tagged (some had acoustical transponders surgically implanted) have gone back to their schools telling alien abduction stories about being caught, brought up to the alien craft and having painful surgical procedures done to them before being released :eek1: