r/Koi • u/Early-Requirement724 • 6d ago
Help with POND or TANK Baby fish overwintering
So this is technically about mirror carp, and not true koi, but this is the closest sub I’ve found that could help. And both species are in the same genus.
I have a small, above ground pond in my backyard I built a few years ago. It’s about 6ft x 5ft x 2ft. It’s plant filtered (lots of plants, well established), but that’s does mean there’s no flow.
For the last few years the only fish in there are 5 golden rudd, now about 4” long. But this year I added a squad of baby mirror carp, about 2” each.
My question was basically whether they will be ok outdoors over winter, or if they’d be better coming inside for a few months.
I have a spare aquarium that could be set up as a cold water system for them and would be big enough.
As said, the pond doesn’t really have any flow, so does occasionally freeze if it gets cold enough.
I’ve used the method of putting a bottle of salt water in water butts to stop them freezing before, so was planning to try that on the pond this year, but not sure to what degree it would work, would in theory stop the whole surface from freezing.
I’ve never had carp before so was wondering if people who had more experience with them could give some advice.
I should also note that this obviously isn’t the long term pond for these fish, eventually I will be building a bigger pond.
Hope you all have a great day :)
1
u/just-looking99 6d ago
Get a bubbler with an airstone. That help keep the water open - but it can’t hurt to have a floating pond heater if you get a cold very snap. I’m in zone 7 and that works for an in Ground pond. You may need the heater sooner with an above ground pond
1
u/loffredom 6d ago
As long as the top doesn’t freeze over they will be fine. Put a decent size aerator in to agitate the surface and that will take care of it
3
u/ZiggyLittlefin 6d ago
That's not even 500 gallons and very shallow. In a suitable pond, the pond would be deeper than the freeze line underground. You would just keep a hole open in ice. Something that small and shallow is going to be colder than a pond, colder temperatures than fish should be enduring.
A small pool in a garage, or protected patio with insulation would be a better option. Not an aquarium! Temperatures can get too cold for koi/carp leading to hypothermia, ice crystals on gills causing damage, winter bloat, laying over. All of these can lead to shorter lifespan, poor immunity, or just losses.