Do fish feel pain?

[Grinch]

Whether or not fish feel pain is the subject of debate in the scientific community. Since the answer to this debate is of great importance to us as fish keepers, especially those of us that treat our fish as "wet pets", I decided to share what I know about the academic debate. I have tried to synthesize and paraphrase the arguments below. A great source of information on this issue can be found here:

http://animalstudiesrepository.org/animsent/vol1/iss3/1/

Note that the above link is to a peer-reviewed academic article and the links below it are not references, they are responses/commentaries from other scientists that are not peer-reviewed. This is just a convenient source of information. There are peer-reviewed published articles on both sides of this argument.

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On the “fish do not feel pain” side, the argument goes like this:

1) Pain in humans is associated with the neocortex, fish do not possess a neocortex, therefore fish are incapable of pain
2) Humans are too quick to assume a fish experiences injuries etc. the way a human would.
3) Aversion to a stimulus does not necessarily mean the fish is in pain.

On the “fish do feel pain” side, the argument goes like this:

1) Fish cannot tell us whether or not they are in pain, so we can’t tell if they are or not.
2) The structures of the brain associated with pain may be different in fish and humans.

Lately the debate has shifted to “What should the null hypothesis be”? In other words, what should we assume about fish and pain in the absence of any information on whether fish experience pain the same way we do?

1) Fish do not feel pain.
2) Fish feel pain.

The null hypothesis (Ho) is generally taken to be that there is no difference or relationship between two things. The null hypothesis might also written as the two things being compared are the same, since there is no difference between them. The alternate hypothesis (Ha) is that two things ARE different from one another or that there IS a relationship between two things.

So, which of these sets of hypotheses is correct?

Option 1 (the "fish don't feel pain" camp):

Ho: Fish are incapable of experiencing pain
Ha: Fish are capable of experiencing pain

Option 2 (the "fish do feel pain" camp):

Ho: Fish are capable of experiencing pain
Ha: Fish are incapable of experiencing pain

In other words, in the absence of new information, what is the safer assumption. Fish feel pain or fish do not feel pain?

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Further background reading on this issue can be found here:
https://en.wikipedia.org/wiki/Pain_in_fish

 

[Wailua Boy]

I think fish have a demonstrated stress response and therefore do feel pain. To what level, only a fish would know. lol

 

[skjl47]

Hello; My guess is they feel a stimulus that is very much like pain even if in some ways it is not quite the same as the stimulus we people consider pain.
A difference in the outer surface of the body may cause them to be less sensitive to fine stimuli. Scales may register more as pressure up to a higher point of intensity that for us. By that I mean we are likely to be more likely to sense pain at a lower threshold. I do imagine that at some level a fish senses pain.
There also may be much more sensitive body parts much as with us. Fins ,eyes, barbells, gills would seem to me more likely to be sensitive.

This consideration is among the reasons I stopped using live bait when I fish. The question remains about how a hooked fish may sense pain. I hope, but do not know, that the mouth parts are not very sensitive to pain. I have gone to artificial lures which are seldom taken very deep and most of the time only hook in the outer mouth parts. These parts do not bleed and by the nature of the things a fish may eat in the wild may not sense a hook the way I do on the several occasions I have hooked myself.

I do suspect any part that bleeds will be pain sensitive.

How to determine such an answer to the fish & pain question is the rub.

 

[J. H.]

How do you know other people feel pain? I have seen fish show signs of being lonely, hot, cold, scared, confident, and I can sometimes even think I feel what they are feeling, but who knows? At this point it has become philosophical. The german philosopher Immanuel Kant has what to say about this.

Kant's "Copernican revolution", that placed the role of the human subject or knower at the center of inquiry into our knowledge, such that it is impossible to philosophize about things as they are independently of us or of how they are for us;

 

[Drstrangelove]

I don't really know the author was thinking? Did he mean emotional pain? Few if anyone have claimed fish feel remorse, anguish, or depression.

Or did he mean physical pain? Most animals, even those of only a few cells, react to harmful stimuli. Is that not pain?

Is this author trying to claim (again) that humans are unique because part of our brain is larger on average that others in the animal kingdom. Haven't we gone down enough of these roads in the last 5 centuries to be a little more humble when we make blanket absolute statements like:

"Only humans can report feeling pain."

I'm going to put that right down next do:

1) Humans live at the center of the universe
2) Only humans make tools
3) Only humans use language
4) Only humans have intelligence
5) Only humans bury their dead
6) Only humans dream
7) Only humans make war
8) Only humans kill for fun

 

[philipraposo1982]

As smart as we think we are we sure have made so horribly stupid claims about other species and our own.

If fish don't feel pain than why spaz out when another fish attacks them? Why do they cower in fear at the top of the tank only hoping to not get attacked again?

 

[Grinch]

"Only humans can report feeling pain."

I'm going to put that right down next do:

1) Humans live at the center of the universe
2) Only humans make tools
3) Only humans use language
4) Only humans have intelligence
5) Only humans bury their dead
6) Only humans dream
7) Only humans make war
8) Only humans kill for fun

I agree with the sentiment that "humans are superior and unique" is a fallacy. The argument that Key makes above (in the linked article), that "only humans can report feeling pain" is a little different though.

In the "fish don't feel pain" camp, one of the arguments is that we can never truly understand the way another species thinks and perceives the world. Indeed, as J J. H. mentioned above, it can be really hard to figure out if individuals think/feel the same way as other individuals within a species. But to Key's point, humans communicate best with humans, so humans are in a better position to understand other humans. Humans don't communicate very well with fish, so it is hard for a human to understand how a fish feels or whether it is in pain etc. To Key, this means that you can only learn about a fish's behavior by examination of the physical structure and activity of the brain. Because fish lack a homologus structure for the neocortex, they must therefore not experience "pain".

 

[Grinch]

As smart as we think we are we sure have made so horribly stupid claims about other species and our own.

If fish don't feel pain than why spaz out when another fish attacks them? Why do they cower in fear at the top of the tank only hoping to not get attacked again?

Key might argue, correctly or not, that "cowering in fear" is not actually an expression of fear so much as it is an evolutionarily conserved behavior. An automatic response to a given situation that is "pre-programmed" into fish by a long history of natural selection.

Key would certainly argue that there is no evidence that cowering in the corner is actually motivated by "fear"... which to him would be an example of assigning a human emotion to a fish without a reason to do so. Fear is an anthropomorphism, just like pain.

 

[Grinch]

I think fish have a demonstrated stress response and therefore do feel pain. To what level, only a fish would know. lol

Fish do have a demonstratable stress response. You can measure it in their blood and even in the water they live in.

Is stress the same as pain? From a biochemical, behavioral, and physiological perspective, I believe there is increasingly support for that idea.

Apologies for the multi-post

 

[J. H.]

Because fish lack a homologus structure for the neocortex, they must therefore not experience "pain".

I don't know what kind of evidence this is. All it proves is that fish don't feel pain in the same way we do. Noone can describe pain properly, if you want this kind of stufff to look like science, you need a psychologist.