Originally Posted by tadpole
This analogy may have some merit if the pond already has a stocking density too high for the pond's capacity. . . Cold water will retain considerably more Oxygen than warm water and fish metabolism is extremely low at low temps. . . I would need to see more than anecdotal evidence that venting or aeration would be required in an iced over pond with the appropriate fish load.
Couldn't agree more. In a clean pond with the appropriate fish load, and the appropriate depth to leave sufficient liquid water, a few days (perhaps even weeks) of ice is not a concern.
But how many ponds do you see people installing with too many fish, in a 2' deep hard plastic box store liner, with 6" of rotting leaves at the bottom?
Granted, in those situations, surviving through winter is the least of their problems.
Also, while cold water does retain more oxygen, and the fish's metabolism is extremely slow in the cold, the actual volume of dissolved oxygen is still staggeringly low, and can be used up. With everything just right, sure a week or so iced over shouldn't be a problem. Now if you are in a climate that ices over for months, I'd think about it.
Last winter on Long Island, ice would have maybe only closed things over for a few days. But in winters past, I've seen ice cover ponds for a month or more. I used to use that heated ring with the dome over it. But I've found that if I put it over a bubbler, I don't even need to plug the heat in to keep a hole in the ice. Do I need to do all this. Perhaps not, but it is cheap insurance.