Frozen fish

[Mike Barnes]

Advice that I've heard suggests that it's a good idea to make a hole in the ice covering a fish pond, to relieve stress on the liner and to allow the water to breathe (oxygen in, farts out). The wrong tool for the job is a hammer; the right tool is a pan of hot water or an electric heater.

I do this every year but I suspect that it's really only necessary for small ponds with rigid liners or lots of fish. Our pond is quite large (6m x 4m x 1m deep), with a flexible liner and not many fish (roughly

150 @ 8cm), so I suspect that I might be wasting my time and electricity.

Comments?

[John]

I thought that floating a few small footballs was a recommended way of introducing some flexibility.

[matthelliwell]

I let my pond freeze over before, didn't seem to do it any harm. Usually I just leave the air pump running with the bubblers raised off the bottom of the pond as well. The trouble with doing it by hand is that a. Its cold outside b. It freezes over again.

Matt

[Chris Hogg]

There's a thread on this very topic on rec.ponds.moderated, started by yours truly. Kate Humble on Autumnwatch (BBC) says it's not necessary to make a hole in the ice, fish will be OK, and two US subscribers tended to agree, but cautioning that it rather depends on the size and depth of the pond, implying that a small pond might freeze right through in a really cold winter (such as they get over there).

[Mike Barnes]

Chris Hogg :

Uncannily similar posting. :-)

That's what I thought but it's nice to have it confirmed, kind of. I don't think our pond would ever freeze all the way through, and in any event the fish aren't particularly valuable - I only got them to keep the insect population down in summer.

I notice that a heron has been peering optimistically down the hole all morning. They don't get fish even in summer, only frogs. How do they survive prolonged cold spells?

[Vortex7]

We have a large pond and the ice was very thick (~4") back in the January freeze.

We just left it and the fish life survived perfectly.

[Pete Zahut]

Our waterfall runs 24/7/365 so there's always a decent 'hole' in the ice there. Earlier this year though, in the 'big freeze' we had the house rewired and the supply to the garage was off for 7 days. The ice over the whole pond was 6" thick but the fish survived OK.

[fred]

Went ice fishing in Canada once. I caught the first fish with the auger, frozen fresh in the ice. What odds I wonder?

[Andy Dingley]

I have some chunks of white polyethylene foam packing (not polystyrene), carved into a school of Moby Dick lookalikes.

Tie them down to keep them central, otherwise they end up uselessly at the side.

[Dave Liquorice]

Hum, not sure that is a good idea, it'll tend to make the water circulate.

The OPs 6 x 4 x 1m deep pond is not very likely to freeze solid like a small shallow one might. Part of the reason for this is that water has it's highest density at about 4C so as the water cools it sinks to the bottom and stays there, water below 4C is less dense so stays on top of the relatively warmer water. This is why I'm not sure that stiring the pond with an aerator is a good idea...

[geraldthehamster]

Our pond is about 12 feet across and 2 1/2 feet deep; it froze last winter, though not all the way through. We made a few half hearted attempts to make holes in the ice, using the tin can full of hot water method, but they soon froze up again. Come the spring, I removed 11 dead fish (out of around 35), and three dead frogs.

Cheers Richard

[geoff]

In message , Mike Barnes writes

I have a small pond and I don't bother breaking the ice. Fish are cold blooded, their metabolism slows down, they don't require much oxygen

[geoff]

Yes, a bit warmer at the bottom, keep it that way

[robgraham]

t's a good idea to make a hole in

I have a small pond - 12ft one way 8 the other and nominally 3 ft deep. This froze quite extensively last year (Edinburgh area) and I expected the koi in it to 'hibernate' at the bottom. After about 4 weeks there was a bit of a thaw and the shallow end thawed out - the fish all immediately appeared there despite the cold and I assumed that the oxygen level in the main body of the water had sunk so low they were surfacing to get 'air' and I put the system pump on the circulate in some fresh water and air.

I'm probably going to have to do the same shortly this year as the ice is pretty thick - mind you it won't be that easy as there's 15"+ of snow now and that's only 10 miles from the sea. I keep on thinking the pond water level has sunk but in fact it's the surrounding surface level that has risen.

Rob

[Ian Stirling]

Your mileage may vary.

I have a pond that's on the order of that size, but twice as deep.

I had a little bubbler going under the water, several feet down. This worked well. Unfortunately, I was feeling crap, and diddn't check it was still working - it wasn't - I'd forgotten to plug it in.

Lost quite a lot of nice goldfish and koi.

100% of them killed.

They were fine for the first snap that just lasted a week or so frozen. Three weeks killed them dead though.

I recommend a bubbler or two under the ice - however ensure that it's actually working - and site the inlet in some place cold but dry as much as you can, to avoid icing on the pipe.

Fish as seen in

yes, it was heavily stocked. Some would say overstocked, but water quality tested good every time I tested it, and there were no health issues before they all died. :)

[matthelliwell]

I've got the aerators and the pumps raised nearer the surface in this weather so it shouldn't be mixing up the lower layers of the pond. The fish all seem happy enough in the trench at the bottom of the pond so I think the water down there must still be the warmest.

Matt