Do Fish Feel Pain?

Do Fish Feel Pain?

Do fish feel pain? Since a fish has a brain, the most obvious answer would be yes. The reason is that if you have a brain, you have the ability to feel pain. Dogs, cats, humans, all have brains and they feel pain. So yes, fish might feel pain but if they do, they are not able to show it like cats, dogs, and humans do. They might just feel pain a bit differently. The jury is still out with the verdict to this question.

What is Pain to a Fish?

The general definition of pain is a distressing feeling that is often caused by damaging or intense stimuli, injury, or illness. It can be generalized or localized and cause the body unpleasant sensations. Pain can be emotional distress or physical discomfort ranging from mild to severe.

Looking at this general definition, does this answer the question as to do fish feel pain? Put yourself in the fish’s place and imagine what it would feel like to get a hook stuck in you, but then some may have felt this pain if they have accidentally hooked themselves. Fish cannot breathe out of the water so there has to be some pain there not being able to breathe.

Do Fish Feel Pain?

According to some research done, some scientists feel that a fish lacks the necessary brain power to process what pain is and how it feels. A fish has a minimal number of pain receptors but they are not sufficient enough to indicate to the fish that they are in pain. The question is how true is this research? When this research was done, it was on trout that was hooked and then released. When released, the trout continued with their activities as if nothing had happened so they figured that it did not cause the trout any pain. If it had, then they would not have been able to resume their normal activities so quickly. They feel that their brain is not developed enough for a fish to feel pain.

Others feel that in order to feel pain, a fish does not need a well-developed brain. They feel that the brain of a fish is sufficient to experience pain. Fish do not have a neocortex as humans but this is not sufficient evidence to prove fish do not feel pain. The neocortex is the part of the brain that is involved in sensory perception, which would help to measure or tell something it is in pain or feeling pain. Some feel that you should also look at the behaviors of the fish and not just at their anatomy.

It is possible for a brain to function differently across species. This is called adaptation and means that different species can feel pain differently. For example, some have noticed that though a fish cannot scream, they grimace when you rip the hook from their mouth. The ones that have seen this grimace on a fish’s face feel that you do not need much more evidence to prove that a fish feels pain. 

Some scientists have experimented on fish, exposing them to some very irritating things and they made note that fish responded in a similar manner the way anything in pain would react. This included rubbing the spots affected against the tank, gills beat faster, and losing their appetite. Fish do have a nervous system so scientists figure that a fish would feel some pain because of having a nervous system They have found that a fish has neurotransmitters. The primary purpose of these is to help alleviate pain by producing endorphins. If a fish was not feeling pain, why would they produce them since they are natural painkillers?

Some scientists have done a detailed map marking more than 20 receptors all over the fish’s body, including their mouth and head. Where the barbed hook goes in their mouth, there are these receptors so this would mean that the fish would feel some pain when they try to get off the hook or it is pulled from their mouth.

Criteria for a Fish Feeling Pain

According to research done, fish fulfill several criteria that have been proposed to indicate that non-human animals, like fish, do experience pain. Those criteria include:

  • Suitable sensory receptors and nervous system
  • Reduced responses to noxious stimuli when they are given local anesthetics and analgesics
  • Opioid receptors
  • Physiological changes to noxious stimuli
  • Exhibiting avoidance learning
  • Displaying protective motor reactions
  • Making trade-offs between other motivational requirements and noxious stimulus avoidance

A fish, according to research done, has nociceptors, which is the ability to detect noxious stimulus that evoke a reflex response in the affected part of their body. They also have a brain with the nociceptors linked to their brain. 

Studies Done

Over the years, there have been many studies done trying to solve the age-old debate of whether a fish feels pain or not.

  • In one study, fish were injected in their lips with an acid solution or bee venom. Immediately the fish started to rub their lips on the bottom or side of the tank, breathing at a rate that is comparable to a fish that is swimming at top speed and rocking side to side.
  • In another study, after the fish experienced a painful event, they demonstrated avoidance or defensive behaviors. The ones doing the study felt that this indicated that the fish felt the pain and remembered what caused them the sensation of pain.
  • Trout are known to avoid anything new or unfamiliar. When the scientists gave the trout an injection of acetic acid and then dropped brightly colored Legos into the tank with them, they did not exhibit this type of defensive behavior because they were possibly distracted by their own pain or suffering. When the trout were injected with morphine and acid together, they maintained their usual caution. It appeared that the morphine, like all analgesics, dulled the experience of pain but did not remove the pain source itself. They figure that the behavior of the two different studies of fish reflected their mental state also and not just their physiology. The morphine should not have made a difference if the fish were responding to the presence of the acid reflexively as opposed to the trout experiencing pain consciously.

With all the various studies done, many veterinarians and biologists are starting to accept that fish can feel pain but there are still some that feel that fish do not feel pain. Some feel that it was just a reflex that the fish acted this way. 


Some scientists and researchers feel that the most silent sufferers in the world when it comes to pain are fish. They do not have vocal cords to let you know when they are in pain or any other way to let you know. All research that has been done indicates both sides of the coin. Some research indicates that fish do feel pain while others indicate that they do not. If you are an avid fisherman and it bothers you to think that a fish feels pain when they are hooked or suffocating when out of the water too long, then you may trick your brain in some way to think that fish do not feel pain. Others may think that fish do feel pain and will not go fishing for that particular reason.

It is up to the individual to look at all the research and then decide if a fish feels pain or not. There is much research out there that can indicate both sides of whether a fish feels pain or not. At this time there is no clear definitive answer so it is up to the individual to decide if a fish feels pain or not. Some feel that if a fish does not feel pain, then they do suffer from the stress of being subjected to noxious, or harmful, stimuli like getting the hook in their mouth.

If you feel that a fish can feel pain, then care should be taken to make sure that when handling them that you do not damage their sensitive skin when removing the hook to release them back into the water. If you are going to keep them, then they should be caught and killed humanely as possible with little to no suffering.

This question when put in front of fishermen and animal-rights activists will give you two different opinions. Most fishermen do not feel that fish feel pain while the animal-rights activist will say they do. Fishing, for many, is a job and without it, they would not be able to feed their families nor would we have fish to eat. Eating fish is no different than eating other animals. Most will argue that if they have a brain and nervous system, they will feel pain. Do fish feel pain is a question that will never have a definitive answer and will continue to be a debatable issue for years to come.

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