If this is your first ever winter as a novice fish keeper you should have by now cleared the bottom of your pond of dead leaves and detritus and given your filter one last clean before winters onset
As if by magic with the clocks set to go back here in the UK the nights have started to grow longer and colder than the mild time we've all been having lately [I'm unsure about the US, just reporting what weve observed here], as such we're starting to take a dip in temperature.
In response to the longer night we have shed approximately 1c. As the nights grow longer and colder we should shed a futher 4c to 5c between now and January but our insulated policarbonate roofing sheets sitting above our pond should keep out all but the coldest temperatures. By that time we expect the temperature on the pond to drop to between 9c to to 7c. As we drop to and then passed 10c then our feeding regieme will stop having already dropped passed 10C.
For any first time keepers on your first ever winter the thought of not feeding your fish may be worrying but as the winter progesses the koi or goldfishes metabolizms will be slowly shutting down to the point that we stop feeding again till the spring.
Again for those on your first ever winter this also necessitates a change in their food, we change from their summer feed to winter feed around the start of October to feeding our koi Wheatgerm and garlic untill the 10c cut off .
Why must we stop feeding at 10c? Both Goldfish and koi are members of the Cyprinid species of fish and as such do not possess a stomach and instead process their food through their intestine, so as the temperature keeps dropping it is vitally important that no food is left in the intestine least it start to rot which could ebdanger your Koi / Goldfish's life which obviously we dont want.
Should your pond temperature continue to drop past 10c to in some cases for ponds without covers around 2c your fish are nearer to being dead than alive but as long as your pond is deep enough to survive a freeze I can asure you that your fish will survive in a torpid state until your pond temperaure creeps back up again.
You must remember however to maintain a hole in the ice so that as the ammonia builds it can gas off which is vitally important.
After the temperature rises in the spring to above 10c [ give it a few weeks to stablize] you can then begin feeding your fish again.
Continue with the wheatgerm and garlic to late spring early summer when you need switch to a food with a higher protien.
Why feed wheatgerm and garlic? Well for one it is easily digestable two it goes along way to protecting your fish from any parasites.
I hope this goes part way to helping the novice help his/her fish survive "good luck".