Fish have the same nerve endings as mammals and can feel pain, British scientists have concluded.
Researchers injected bee venom into the lips of rainbow trout and the fish reacted in the tests by rocking and rubbing their lips on gravel and tank walls.
Dr Lynne Sneddon claims these behavioural changes are not reflexes but signs that fish can feel discomfort, challenging previous thinking that fish brains are not developed enough to experience pain.
Fish farms should now be regulated in adopting humane methods to slaughter fish, an animal welfare group has responded.
Are the reactions just reflexes or are fish really suffering? Should this change our attitude toward fish? Should angling be banned? Should fish farms be regulated?
This debate is now closed. Read a selection of your comments below.
Go into the countryside and look at road kills, wild deer tangled in old cassette tape, swans injured by power lines, rabbit warrens caving in under the feet of walkers etc - the list is almost endless. At any point where one species interacts with another, regardless of whether it is for food, pleasure or accidental, pain will be caused. It is a fact of life, get over it and get on. You may as well try to ban domestic cat ownership - that causes a greater degree of suffering to wildlife and to species that we know can feel pain.
Simon Hawksley, England
So fish feel pain. What a revelation! I act like the trout after three seconds of exposure to EastEnders. Are Rights Groups going to march to ban every activity because someone, or something feels pain? Next up - gardening. Weed killer will be considered "inhumane" and grass cutting and pruning will be akin to mass decapitations and amputations!
Robert Duncan, United Kingdom
If the fish are eaten, that is exactly the same as any farm and therefore has purpose. Sport fishing should be immediately banned. However, it won't be, because fish are not cuddly like foxes and fishing is considered a Labour supporters' sport.
Anglers are generally gentle souls
Anglers are generally gentle souls who remove the hook quickly and kill the fish decisively if they are going to eat it, or return it to the water swiftly. Don't forget there are at least three million regular anglers in the UK (and Jeremy Paxman is one of them!).
I enjoy fishing and yes, I know it hurts them, but I'm not going to stop. Life is hard and cruel and it's only tree-huggers who think they can change that.
David Cobern, Exeter UK
All animals must be able to feel pain in some form so if you crunch a beetle will that be the next study or should gardeners watch out when digging? Dump the pointless studies and do something constructive with the MONEY. After all, they hurt the poor animal with trying to find out if it did feel pain.
Yes, as a person who has been fishing, I believe that fish could feel pain. When you take the hook out of a fish mouth which you want to throw back it seems very distressed. I think this is the pain of the hook and the pain of not being able to breathe. I don't believe fishing should be banned, but controlled more to protect the resource for further generations.
South Africa (living in London)
The most boring hobby in the history of human existence
Not only is fishing cruel, but it is quite possibly the most boring hobby in the history of human existence. Can anyone give me an honest justficiation for fishing which will prevent me from pointing and laughing at them?
Dan Mead, Surrey, UK
It seems naive to have assumed fish can't feel pain as we have established that all other life on this planet can! Fish farms need to be regulated on this issue and also to help reduce the spread of disease, genetic problems and the high uses of chemicals which impact not only on the fish, but on all of us. We really need to sort out all farming.
It's pretty obvious that a living creature should not be abused for human enjoyment, it's amazing that in the year 2003 people still get their jollies by torturing fish!
Tomas G, UK
Who's taking bets on how quickly this enters into the "class" argument? The fox hunting issue has been centred on political and class envy, often losing sight of animal welfare. If fish feel pain much more readily than we supposed, then it is immoral to ignore that. Will the new Labour machine be so forthright over this issue knowing how many angling Labour voters are out there? Come on Tony - what's good for the fox is good for the fish! It's flies, wasps and spiders next.
Paul B, UK
It'll put an uncompetitive strain on UK fish farmers
I have no doubt that fish feel Humane methods to kill farmed fish are not really workable in a global economy as it'll put an uncompetitive strain on UK fish farmers. Everyone will head to the supermarket and buy foreign fish imported cheaply because of a lack of similar controls overseas. More or less what's happened to our meat farmers really! You can't ask meat and fish farmers to take steps on cruelty unless we in turn are happy to pay more for it.
Phillip Holley, UK
Whoever decided in the first place that fish are not sentient beings? My despair at human cruelty and arrogance is reinforced today by the report on cruelty to animals in the UK. Britain, supposedly a 'nation of animal lovers' is slipping gradually back into the Dark Ages.
Perhaps they do, but it's not going to stop me eating them.
Of course they feel pain, even if it is only emotional pain. Imagine as a human having food hung in front of you. As soon as you go to eat it a sharp object punctures your mouth and you are dragged away from all you know.