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I've encountered a clip on Youtube showing a goldfish thrown in liquid nitrogen and immediately after to normal water and swimming normally. In the explanation to the clip it says:

For everyone that is worried about the goldfish, it survived and was perfectly fine until we fed him and a few of his friends to our turtles. (Which is what they were bought for in the first place!)

I am wondering now as to several issues.

If the goldfish wasn't fed to the turtles and was allowed to live out its life, would it suffer any long term damages from the act?

Is time an issue here, if the fish was kept frozen for a longer time, would it suffer more damage and would it be able to be revived?

Is the size and nature of the fish's body a factor? Would a larger animal or an animal with better resistance to frost that would take more time to completely freeze have damage due to gradual freezing of body and systems?

Does the fact that fish have cold blood affect the result of the experiment?

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    $\begingroup$ As a kid ice fishing in Michigan, I would catch yellow perch and throw them on the ice. They would flop a few times and freeze solid. Temp. was around zero. Some time later, 1/2 to 1 hour I carried them home in my pockets and put them in tap water so they could be scaled. Much too my surprise after about 1/2-3/4 hr. they started thawing out and started swimming around, some advanced stages of others. True Story many years ago. I have no knowledge if they had Drain Bamage as I eventually ate them. True story many years ago!!! Walter Sharp $\endgroup$
    – user14651
    Feb 25, 2015 at 23:51
  • $\begingroup$ Well, as and you can see the fish just "froze" for max 2 seconds. It is normal to live because it didnt die from cold. $\endgroup$
    – The_Mad_Fish
    Jan 3, 2016 at 21:32

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I have no idea what's the real reason for the survival of the poor fish, but I would guess this is all in the timing. I know for certain ;-) that one can submerge a hand in liquid nitrogen for a short time or in general one can pour liquid nitrogen on the skin with no harm done whatsoever.

The reason is that the difference in temperature that interface (-180 deg C or so for liquid nitrogen and 20-30 for the skin surface) is so large that nitrogen vaporizes instantly and does not penetrate/affect the tissue. The demonstrator could have pulled the fish with bare hands.

I think that for the goldfish the time was too short and while it was cooled/shocked a bit, it might have been too short to do any serious damage. But -

As a scientist, I can't help but notice that we don't really know the condition of the fish before or after the liquid nitrogen 'treatment'. We only see it flapping for a few seconds when back in water. I wonder what happened to the eyes and the mouth, both quite sensitive tissues for such a shock. Also, the water the fish was in was a factor probably, providing additional buffer between the fish and the liquid nitrogen.

Last but not least, the ethical committee quite certainly did not approve that demonstration.

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    $\begingroup$ Of course we do not really know whether liquid nitrogen was really in the other pot... we just see smoke $\endgroup$
    – nico
    Apr 19, 2012 at 20:50

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