Can fish feel pain?

“The question is not, Can they reason?, nor Can they talk? but, Can they suffer?”
– Jeremy Bentham, 1789

For centuries, people thought fish were so different from humans and other animals that they couldn’t feel pain.

After all, their brains and nervous systems are very different from ours. In the past, scientists thought that fish simply respond to stimulus (something that causes a physical reaction) in much the same way a plant would.  For example, some plants’ leaves will fold up when you touch them.

But, unlike plants, fish do have a central nervous system and that system has special receptors, called nociceptors, that detect injury or damage to the body.

It’s the same kind of receptor that makes us pull our hand away if we touch a hot pan on the stove.

But having nociceptors doesn’t prove fish feel pain. Scientists had to establish whether the signals that a fish’s nociceptors send to its brain create the unpleasant state that we know as pain. In recent years, ground-breaking research has been done to determine just that.

In one experiment, trout were injected in their lips with bee venom.

They began breathing faster and lost interest in food. Some began rocking back and forth on the bottom of their tank and rubbing their lips on the side of the tank. 

But these behaviours, which are indicators of distress, were dramatically reduced when the fish were given morphine, a painkiller. 

It’s known that morphine dulls pain but doesn’t remove the source of pain itself, which indicates that the fish’s behaviour reflected how they were feeling, not just a physical reaction.

In another study, fish that were again injected with bee venom appeared to be distracted by pain.

They stopped showing normal cautious behaviour when a strange object (a block of red Lego) was dropped into their tank. When the fish were given painkillers they resumed their normal wariness of the foreign object.

These and other scientific studies have led respected animal welfare organizations to conclude that fish can feel pain. The American Veterinary Medical Association, in its guidelines for the euthanasia of animals, states that: “Suggestions that fish responses to pain merely represent simple reflexes have been refuted by studies…”  The BC SPCA’s Position Statement on Fish and Aquatic Invertebrate Welfare states that:

“The balance of scientific evidence indicates that fish and cephalopods (e.g., octopuses, squids) are sentient, capable of experiencing pain, fear and distress.”
BC SPCA’s Position Statement on Fish and Aquatic Invertebrate Welfare

Content warning

The following video contains video footage of commercial fishing operations from 2:01 to 2:37.

What Fish Feel When They Are Killed for Food | NowThis

Watch this heart-wrenching video about how fish are killed for food despite proof that they can feel pain and emotion. ” Subscribe to NowThis: ” Sign up for our newsletter KnowThis to get the biggest stories of the day delivered straight to your inbox: In US news and current events today, this NowThis News video is exploring the question, do fish feel pain?

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