I have a fishpond. It has Goldfish in it. I have kept the fountain on, to keep the water in a liquid state. Too bad that around the edges of the flow, the water is frozen solid. There is clearly a Goldfish frozen in there. Someone where I work, (who should know about these things), says it will survive. Come the spring thaw, it will be as good as new. I don’t buy it. How can a fish freeze solid, and then just go on about its fishy business weeks later? I’m thinking that when a cell is frozen, the liquid inside it expands and the cell bursts. Since the fish was not flash frozen, its cells must have all ruptured by now, and the fishy will never more swim ‘round this mortal coil.
Some fish have a natural version of antifreeze in their blood and tissues. The problem is that the fish still needs to pass water through its gills and eat to stay alive.
GOLDFISH
In its natural habitat can spend winter months sealed, with no oxygen under pond ice. It depresses its metabolism by 90 per cent, swimming slowly, like a runner, it uses glucose as an anaerobic energy source. Unlike a runner it gets rid of the toxic waste lactic acid by converting it to alcohol and peeing it away. Low oxygen tolerance made goldfish the world’s first aquarium fish a thousand years ago.
We have goldfish. Our pond frequently freezes over (we always turn the circulation system off in the winter). The goldfish do just fine. The pond sometimes appears to be frozen solid (when we’ve let the water level get low), but I’ve never drilled down to find out if they’re actually encased in ice or if they’re in a few inches of water at the bottom.
I have been forbidden to thump on or otherwise vibrate the ice. My pond-tending partner swears that, in her experience, it will kill the fish.
We usually quit feeding the goldfish once it gets cold - they won’t eat and it mucks up the pond.
Just because the goldfish is encased in ice doesn’t mean its own tissues are frozen. Cell contents have a higher concentration of dissolved materials, and thus their freezing point (like that of salt water) will be lower than that of fresh water. (Some amphibians, in particular the Wood Frog, can survive having their tissues frozen, but I doubt this is true for goldfish.)
If a goldfish was frozen in the ice, but unfrozen itself, its body temperature would be so low that its oxygen and food demands would be very low. However, I doubt that a goldfish could survive for an extended period in this condition.
This means exactly that. And let me tell you, they’re none too happy when it happens. This is why it’s best to get them in the oven as soon as possible. The heavy oven door muffles their screams.
I’ve seen this as well in friends’ ponds. Knowing this is the case (or believing it is anyway), I wonder how the fish got frozen in Janx’s pond. Doesn’t seem likely that it got caught napping while ice formed on it. And if Janx’s pond is a typical shape, it doesn’t seem like ice would form in some box that would slowly enclose the goldfish more and more tightly.
Perhaps it died of natural causes and then got caught in the freeze.
You probably realise this already, but whatever happens, do not attempt to intervene; don’t try to extract it from the ice or even thaw the ice by artificial methods; the fish might already be dead anyway, but attempting to rescue it is sure to remove all possibility of a satisfactory outcome.