We are looking to take healthy koi and a healthy pond into the winter months,
so that we do not get problems during the winter when we cannot treat efficiently
and the so-called 'spring start up' problems.
Right now, mid September, the koi are eating like pigs and trying to build
up energy reserves, fats and glycogen, for the winter but as soon as the night
time temperature drops then the koi feeding should be dropped by half. If
you have been feeding 6 times per day then drop this to 3 times per day and
gradually tail that off so when the temperature reaches 55 f, you are not
feeding them at all.
If "you" feel cold then so do the koi as the koi's body temperature is controlled
by the temperature of the water in which it swims, it cannot generate it's
own body heat.
The standard water temp to stop feeding koi is 55f, however, the koi will
instinctively know when its too cold for it to eat and I find my Koi will
refuse to take any food when it is too cold for them to digest it. Watch your
koi when you feed and see how unenthusiastic they are about food and don't
leave the food floating on top of the water, as it will sink to the bottom
of the pond and decompose releasing toxins.
Koi do not have a stomach as we (humans) do, they utilize their gut which
in an adult koi will be approx. 2.5 times the body length and if the food
is not digested by the koi then it will lie in the gut and rot.
It is better to feed a 'good' wheat germ food, as the koi don't need so much
protein at this time of year. There is enough crude protein in carbohydrate
food to keep the koi going, also whilst eating carbohydrates the koi do not
produce much ammonia at a time when the filter is at a 'low', this is a good
thing.
Sorting the koi out for winter is fairly easy to do. If you have a microscope,
obviously scrape and scope and see if the koi is carrying any unwanted passengers
such as flukes and ich. Treat accordingly, bearing in mind that some meds
don't work well at low temps. If you haven't got a microscope then it may
be possible to get a dealer to inspect a couple of fish and get a general
feel for their well being and treat accordingly if needed prior to winter.
Parasites/pathogens tend to be up and running in the spring before the koi's
immune system is, so you can see we have a potential problem.
You can read about these parasites/pathogens elsewhere on this board so I
wont go into how to eliminate them.
Any illnesses or damage on the koi will not have time now to heal before winter
sets in unless the sick/damaged koi are removed from the pond into a heated
tank for treatment. But remember once in the heated system it becomes quite
a task to return the koi to the now colder pond.
Filters;
Winter is an ideal time to sort out any problems that you didn't have time
to deal with in the summer as the koi are on a 'go slow' and wont lack oxygen
(cold water holds more oxygen than warm water) or need the filters so much
if you aren't feeding.
Check all the hardware, joint, pipes, air pumps, pumps, waterways, hoses etc
and of course the filters themselves and repair as needed.
If you are using any sort of ice clearer to keep a hole open in the ice for
gas exchange, which you will need to do, then make sure it actually works
before you need it.
Think hard about making/buying a cover for the pond or if you already have
one make sure that it is not ripped or damaged.
Do not turn your filters off over winter or you will lose all of the nice
bacteria that you have built up in the summer, however you can remove any
air lines that are in the filters they are not needed now as the cold water
contains enough oxygen to keep the bacteria/koi alive. The bacteria in the
filters will assume dormancy to protect them from the cold, ready to burst
into life in the spring.
Thoroughly clean your filters using pond water, back flush them, move the
media around to get all the 'crud', squeeze the matting, get the bits off
the brushes, whatever your do for your system, but make sure it's very clean
other wise all the mess and dirt will decompose and pollute the water.
Any and all water return pipes should be placed under the surface of the water
and waterfalls turned off because splashing water like this gets colder as
it mixes with the cold winter air.
Make sure that the bottom of the pond is free from debris and dirt, this is
where the koi will stay for winter and we don't want them conserving energy
lying in dirt.
The koi go to the deepest part of the pond because they are usually feeling
miserable and so do not remove the pump from the deepest part of the pond
other wise the koi will be lying in undisturbed toxins, ammonia etc. as the
dirt rots.
When the koi are lying on the bottom of the pond try not to disturb them as
they are using the fat (glycogen) reserves to stay alive and don't need to
use up the energy unnecessarily with movement. Don't worry they are not dead,
as dead koi float eventually, even under the ice.
Lastly do a fairly large water change, about 30%, using dechlor to reduce
the bacterial/hormone levels in the pond and to add minerals. Now you are
ready for winter, but don't forget in winter to do water changes and take
the water parameters on a regular basis.
Keep checking the koi and you should be OK.