Kenny Torella

For a long time, the scientific consensus was essentially that fish don't feel pain or much of anything at all.

But it was a belief without a lot of evidence.

A few scientists had really looked into the question.

But in the early 2000s, a small group of researchers at the University of Edinburgh began to think seriously about fish.

And their work has really helped to shift the consensus around fish pain.

They've made a lot of really interesting discoveries.

And the first is that they discovered that fish have nociceptors, which are neurons that send signals to the central nervous system when an animal is injured.

And they also conducted experiments designed to figure out whether fish really feel pain to make sure that they weren't just reacting reflexively to painful stimuli.

And what these researchers found was that, yes, fish do feel pain.

As an example, when they prodded goldfish and trout with needles, they

They showed activity in parts of their brains associated with higher processing.

Or when rainbow trout were injected with painful substances like acid or bee venom, their respiration rates spiked, their appetites dropped, and they rubbed the affected areas against the walls of their tanks in an effort to soothe themselves.

Taken together, this research really shifted the consensus on whether fish can feel pain.

And now the belief that they can't is a pretty minority view in the scientific community.

And just to step back for a moment, what this means is that during the same decades that scientists learned fish can feel pain, the seafood industry began to factory farm them in enormous numbers and in pretty terrible conditions.

If they feel pain, are they conscious?

Are fish thinking, observing their environment, etc.?

Yeah, so to kind of break it down, you know, pain is a sensation that fish can feel, but to experience it, they have to be conscious, or as our colleague Marina Blatnikova put it, to have something that it is like to be them, to subjectively experience the world.

And

You know, what she wrote about is that we can never really know what it's like to be a fish or a dog or even a fellow human for that matter.