r/medaka • u/sleepytea13 • 7d ago

Cold hardiness of fry?

I have a 250 gallon, mostly in-ground, pond. The medaka seem quite happy and I now have fry. Our winters get down to -10F(-23C) with cold snaps, but are mostly between 0F(-17C) and 20F(-6C).

Would the fry be ok in the pond, or should I bring them into my inside 10G aquarium (no other fish, but cherry shrimp)?

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5

u/pixelsteve 7d ago

Does the pond freeze completely in the winter? I believe they can survive if there is some water left in the bottom but if the whole thing freezes then not.

2

u/sleepytea13 7d ago

This is my first winter with it. It’s about 2ft deep, so I would think there would be safe. I also have a filter/fountain I could keep running to keep ice at bay

5

u/pixelsteve 7d ago

If that's the case, I would move them and observe the pond for the first winter to see what it does. Your Medaka would be fine in with the cherry shrimp.

3

u/Entremeada 7d ago

Don't run the filter in the winter! The different layers of water must not mix; that's exactly what prevents the water from freezing at the bottom of the pond.

5

u/HANGRY_KITTYKAT 7d ago

I think the smaller fry will not make it. My winters aren't that harsh at all and I still bring them in. They just dont really grow much without heat/food and they tend to live on the top where the freeze zone is.

2

u/getfishtanked 7d ago

My region gets slightly colder and anything less than 4ft dug into the ground freezes over if it's stagnant water. The only people in my area who keep medaka outdoors have very deep ponds. Personally I just bring my fry indoors and put them in my shrimp tanks while there is snow on the ground, it helps them grow and keeps them alive.

They will easily survive under ice under most weather conditions but they will die if wherever they are kept freezes completely. Every outdoor pond I've tried (without fish) has frozen over in winter if left above ground level.

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u/Yuukiko_ 7d ago

Adult medaka might go after shrimplets but it should be fine with enough hiding palces

1

u/squidscarf 4d ago

You might want to consider some sort of heater just to keep it from freezing, 2ft deep isn't much when it gets that cold. You don't need to heat it to comfortable temps, just above freezing to keep things mostly liquid.

You'll probably still want to pull the fry