Further evidence shows that fish feel pain

http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=2134Further evidence shows that fish feel pain



Picture by Neil Hepworth.
Scientists from Norway and the USA have offered further evidence that fish are able to feel pain.

In a study published in the most recent issue of the journal Applied
Animal Behaviour Science, Janicke Nordgreen and coauthors developed an
apparatus to expose goldfish (Carassius auratus) to controlled,
localised heat in order to test the hypothesis that goldfish perceive
heat as aversive.

The authors also injected half of the experimental group with the
painkiller morphine and the other half with saline as a further test of
this hypothesis, predicting that the morphine-injected fish would be
able to tolerate higher temperatures before showing an aversive
response.

The apparatus consisted of small foil heaters placed in contact with
fish skin, and the heat exposure was safely controlled (with a safety
cut-off at 50°C in the event of equipment failure) to prevent physical
damage to tissues.

The authors observed the goldfishes upon treatment, counting the number
of times the goldfish displayed an escape reaction, defined as C-starts
(movement of the head and tail towards the same side of the body
forming a ‘‘C’’), swimming (movement of the body to form an S-shape) or
tail-flicking (flicking the tail without sideways movements of the head
or trunk region), on exposure to heat.

The scientists found that goldfish displayed an escape reaction to heat
being applied on their bodies, implying that they found it to be
aversive.

They also found that morphine had no effect on the fishes, contrary to
their expectation that the morphine-treated fishes would be able to
withstand higher temperatures before reacting to the pain of the heat.
However, the authors did notice that the morphine did have an effect on
the fishes a few hours after treatment.

According to co-author Joseph Garner, “The fish given the morphine
acted like they always had: swimming and being fish. The fish that had
gotten saline - even though they responded the same in the test - later
acted different, though. They acted with defensive behaviours,
indicating wariness, or fear and anxiety.”

“The experiment shows that fish do not only respond to painful stimuli
with reflexes, but change their behaviour also after the event,” said
Nordgreen

“Together with what we know from experiments carried out by other
groups, this indicates that the fish consciously perceive the test
situation as painful and switch to behaviours indicative of having been
through an aversive experience.”

For more information, see the paper: Nordgreen, J, JP Garner, AM
Janczak, B Ranheim, WM Muir and TE Horsberg (2009) Thermonociception in
fish: Effects of two different doses of morphine on thermal threshold
and post-test behaviour in goldfish (Carassius auratus). Applied Animal
Behaviour Science 119, pp. 101–117.

i read this and i think it was a good exercise but albeit a slightly cruel one

but some would argue that because it was a heat source and fish can be suseptible to heat changes it was just a reaction to the temperature getting nearer

but then their are those that are arguing due to the fact that the fish never felt it/bucked untill it touched them have no sensors to feel a change in temperature as it gets closer until it touches them which would mean they can not feel pain

i am unsure i would hope they dont feel pain due to the lives some lead

Why would it ever have been considered that they didnt feel pain? It's the same argument people made about foxes not being able to feel pain because they weren't sentient and so didnt mind being killed by hounds. Later on though, and a bit of research down the line they had to change their thinking.

everything must feel some sort of pain


dekker

yeah, any living creature can surely feel pain. there's no need to prove something like that.