Re: NANFA-L-- cold euthanasia
Wed, 30 Aug 2006 01:00:14 +0700

For the way you suggest it may not work for air-breathing fishes. I
had tried that with bettas and the result is not good... they seem to
be drown before becoming inactivated... :-(

For slow temp change I remember vaguely about experiment in my bio or
eco class in the US about effect of temp on silversides. Even with
rather slow temp change [1/2 - more than 1 hour] they still show sign
of discomfort [and still died] when temp approach extreme on either
side, but far worse reaction on the warm end.


Jase Roberts wrote:
> Hmmm... Yes, that does sound unpleasant for the fish. The difference here is that Dave's suggesting you put the fish in the freezer with some ambient-temperature water. The water's going to slowly cool and take the fish's metabolism down with it -- so by the time they get to freezing, they're almost completely dormant.
> What you're doing is sticking a fish with a fully-active metabolism into freezing water. That means the fish is aware of and responding to the extreme temperature change.
> If you need to do that, I'd suggest sticking the fish in a small bag of ambient-temperature water, and immersing fish AND bag into a bucket of ice water. That'll chill them more gradually, so their metabolism will go down and they become essentially unaware of the situation before they get to a lethal chill.
> -Jase
> wrote:
> > Sorry for being negative but I am not so sure about the thought that
> > freezing is humane and painless, since often when I put fish
> > [headwater cyprinids] in freezing water and ice to knock them prior to
> > setting their fins and preservation they thrash around violently for a
> > few seconds. This may not be pain but I doubt they are not in extreme
> > stress and discomfort for that few second.....
> >
> > Tony
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