
Why don’t fish freeze to death in icy water? - baalcat
https://www.global.hokudai.ac.jp/blog/why-dont-fish-freeze-to-death-in-icy-water/
======
patrickdavey
Well, that's a funny thing, _some do_, or at least to the point where it makes
no odds. I was touring around Iceland (a country I can highly recommend
visiting) and we were at Jokulsarlon [0] (where the icecap carves into the
ocean) and there were lots of what looked like dead fish there. They basically
swim in from the ocean, seemingly catch hypothermia, and are a feast for
seals.

The local "fishermen" came along, with wellies on, waded into the water,
literally kicked the fish out onto the shore. One of the fishermen was kind
enough to give us one of their catch. It was tasty.

Go to Iceland, it's awesome.

[0][http://blog.psdavey.com/2014/08/25/down-the-coast-to-
jokulsa...](http://blog.psdavey.com/2014/08/25/down-the-coast-to-jokulsarlon/)

~~~
abrowne
Having been convinced by my classmates to jump in with them, I can confirm the
Jökulsárlón lagoon is very cold!

------
ilamont
My dad says when he went ice-fishing with my grandfather they would put caught
fish in a bag in the trunk. The fish would freeze on the drive back home but
as they thawed back in their kitchen they would come back to life and start
flopping around. Others have reported this, too (1). I can only guess their
interiors were not frozen, and just in some sort of dormant state.

We have a small fishpond in our backyard just outside of Boston (kind of like
this one, but a little deeper: [https://www.pondmarket.com/epdm-pond-liner-
rubber-liner-coat...](https://www.pondmarket.com/epdm-pond-liner-rubber-liner-
coatings-sealers/royal-coachman-preformed-pond)). We have a few comets and
shubunkin. Every winter the fish go dormant, usually around late October or
early November, sinking to the bottom half-hidden by dead leaves. The top
eventually ices over a few inches. We keep the small pump going and try to
break the ice bubble if it freezes over, but otherwise the fish are not active
for 4-5 months (with one exception, described below), until warmer weather
comes in mid-April. It's an amazing thing to see them slowly reactivate and
start to take food again.

One winter the pond iced over and they were still swimming around a little (2)
which I can't explain. It's the only time we've seen this in the past 6 or 7
years.

1\. [https://biology.stackexchange.com/questions/1661/fish-
coming...](https://biology.stackexchange.com/questions/1661/fish-coming-back-
to-life-after-being-frozen)

2\. [https://www.instagram.com/p/BAR4PG8pJrn/?taken-
by=ilamont](https://www.instagram.com/p/BAR4PG8pJrn/?taken-by=ilamont)

~~~
madaxe_again
When they thawed in the kitchen, were they perchance on a metal surface, or
salted? If so, what you're seeing isn't resurrectionist fish, rather
electrolysis inducing a galvanic response in the deceased nervous system.

~~~
simlevesque
I think it was more like this:
[https://www.youtube.com/watch?v=zOJZaGUx9JM](https://www.youtube.com/watch?v=zOJZaGUx9JM)

~~~
madaxe_again
Huh. That's a new one to me. This quora link sheds some light on what may have
happened in both situations:

[https://www.quora.com/Is-it-possible-that-a-fish-is-
complete...](https://www.quora.com/Is-it-possible-that-a-fish-is-completely-
frozen-comes-back-to-life-after-submerged-in-liquid-water)

------
ChuckMcM
Hmm, interesting. There was a pond in front of the office at Denver which was
created when construction diverted some of the Platte river, and it had 3 or 4
fish 'stuck' in it. In the winter the water froze solid and I walked over and
saw one of the fish sitting there frozen in the ice. I was tempted to try to
chip it out but it was too deep and the ice too hard. About 3 weeks later the
ice melted and the fish was swimming around again. It was pretty amazing to
see.

~~~
littlehood
Depending on the depth of the pond, it may have not frozen to the bottom -
water has the highest density around 4°C (~39°F).

~~~
douche
If the pond isn't very deep, and there's no streams or anything else coming
into it that would oxygenate the water, usually the fish would die because of
that. Happens all the time around here if water levels change drastically (say
a beaver dam lets go), followed by a hard, cold winter with deep ice.

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teekert
Why would water (inside the fish) freeze in water (outside the fish)? I mean,
the fish are swimming in the liquid form of water which apparently also
doesn't freeze so why is it considered strange that they don't freeze? It
would be strange if they didn't freeze while being in a block of ice, or if
they would be dead blocks of fish-ice floating on liquid water. A non-frozen
fish in liquid water is not strange, or am I missing something? The article
doesn't really clarify it for me.

~~~
stagbeetle
All bodies of water are not created equal.

The specific, and level of, solutes in the water determines the temperature at
which it freezes. Fish are not perfectly permeable membranes, thus the
internal freezing point of fish could be higher than the external freezing
point of the water.

Fish are also cold-blooded and are at the mercy of their surroundings.

~~~
pbhjpbhj
Or in other words you can freeze non-salt water in liquid salt-water; the salt
lowers the temperature at which the mix freezes.

Human blood freezes at about -2degC. Brine can apparently go down to -20degC
(source: Wikipedia).

~~~
dghughes
> the salt lowers the temperature at which the mix freezes.

If you make ice cream the old fashioned way you throw in rock salt to lower
the temperature below 0C.

You can also chill beer cans sitting in water very fast adding piles of salt
to water.

~~~
logfromblammo
You don't actually salt the ice cream. You put salt on ice surrounding the
unfrozen cream. Salty ice cream (with the amount of salt necessary to freeze
it) would be gross.

Available soluble salt ions lower the melting point of the water to the point
where the water-ice would very much prefer to be salt-water at the same
temperature. But a phase change requires energy, too. The energy required to
melt the ice and dissolve the salt is taken first from cooling of the sugar-
water in the cream, then from phase-changing it to solid crystals, then from
cooling the solid-phase materials. If the setup has a paddle, that is mainly
to transport heat from the center of the cream vessel to the conductive walls,
and thereby regulate the size of the crystals.

Cooling beer cans in liquid water by adding salt does not rely on freezing
point depression, but the heat of solution for NaCl in H2O, which also
contributes slightly to the ice cream system above. You want cold beer fast?
Use potassium nitrate (KNO3, saltpeter), as it has nine times the enthalpy of
solution as NaCl.

~~~
dghughes
I know since I've done it I've made ice cream that way, I guess I didn't
explain it very well.

~~~
logfromblammo
Some people have never made it that way, or any other way. Anyone who ever has
made it that way would immediately understand.

What a hand-cranked ice-cream bucket might look like in ASCII diagram world:

    
    
                       |
                  o----o
      ____________|____________
      \\.salt..|~~~~~|..salt.//
       \\######|     |######//
        \\#ice#|cream|#ice#//
         \\####|_____|####//
          \\#############//
           \=============/

~~~
dghughes
The one I have has an electric more in place of the hand crank.

I also used to make it by putting the pot of cream mixture into a deep freeze
still in the metal pot. Then get an electric hand mixer and mix it while it
sat in the deep freezer. I'd do that over and over then for what seemed like
100 liters of milk and cream and hours of work I'd get 500ml of ice cream.

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mauvehaus
I'm going to ask a staggeringly dumb question here:

Since none of the fish on Earth, which survive these conditions, live in zero-
gravity, what is the reason for doing the experiment in zero-G? Given the
immense cost of sending stuff to the ISS, there's clearly something about
doing the work in zero-G that's either necessary, or highly advantageous.

Clearly the effect that keeps the fish alive works just fine under normal
Earth gravity, or we wouldn't have an interesting question to answer.

~~~
isk517
In the article they say that convective flow does not occur in micro-gravity
which makes it possible to accurately measurement the ice crystals as they
grow.

~~~
mauvehaus
That makes sense, thank you. If you're already removing the flow that comes
from the fish's own circulatory system, you may as well remove the remaining
(comparatively small?) effects of the convective flow.

------
flexie
Article says fish survive in sub zero environments such as below ice. But is
the water below ice sub zero? I thougt it was at least zero as long as its
liquid (at close to normal pressue). Is that the salt?

~~~
masklinn
> Is that the salt?

Yes. Oceanic salt water freezes around -2C. (or possibly below as surface
water freezes "pure", the salt content getting transferred to lower layers).

------
intrasight
Some fish have antifreeze proteins:

[https://www.nsf.gov/news/news_summ.jsp?cntn_id=132798](https://www.nsf.gov/news/news_summ.jsp?cntn_id=132798)

