Winter feeding regime

Below *8°C avoid feeding if possible
If you think they want food; they should be actively looking around.  
Wheatgerm only

If your koi are swimming about looking for food, feed them.
They will be burning valuable calories searching for food and to with hold food means that you may weaken the koi for the spring.
Just a few pellets around lunch time, this gives them chance to start some sort of digestion process before dark.

Feed them only as much as they can eat in 10 minutes

*denotes water temperature not air temperature.

 

Spring feeding regime

Below *8°C avoid feeding if possible
*8°C – *12°C feed lightly

Your koi will be avidly looking for food on warm spring days.
This is a dangerous time because your koi will want to eat almost as much as you can throw in but your filters will be underperforming because the cold water of winter has killed off a good deal of the nitrifying bacteria on the media.
Stick to wheatgerm food and feed only as much as they can eat in 10 minutes (you may be able to feed 2 or 3 times a day as temperatures increase).

*denotes water temperature not air temperature.

 

Summer feeding regime

Above *18°C go for it.
Feed them a high quality, high protein food for maximum growth and health throughout the summer.

Throughout the summer, feed them as much as they can eat, you can afford and the filters will handle. Again feed them as much as they can eat in 10 minutes but this may be 10-12 times a day.

Out at work and cannot feed your koi as much as you like consider an auto feeder.

*denotes water temperature not air temperature.

 

Autumn feeding regime

Watch your water temperatures carefully

While the water is warm you can continue with high protein foods but as the temperatures drop reintroduce wheatgerm feed back into their diet.

Feed little and often, take them gently into winter.

For other food that koi can eat here are a few suggestions.