Plenty of people ask this question.
Here is one approach.

Carp will achieve their best growth rate at 6.5% of their body mass per day at 23 deg C. However this will bankrupt you!!!!

The best is to work at between 1% and 3% of body mass. There is some debate around this and you should do some research and settle on figure you are comforatble with and can afford.

relationship between Length and Weight (Koi - Servaas De Kock & Ronnie Watt pg22)
Age - Length = Body Weight
<1yr - 15cm = 60g
<1yr - 18cm = 120g
<1yr - 20cm = 210g
<1yr - 25cm = 350g
1 - 2yr - 30cm = 550g
1 - 2yr - 40cm = 1.1kg
2 - 3yr - 50cm = 2.2kg
2 - 3 yr - 60cm = 4.5kg
3 - 5yr - 70cm = 11kg

You can get an estimate or accurate(bowling them) reading on the lengths of all your fish,
calculate the mass and add it all up.

Ok so if the Total Fish mass 25kg then

25 x 1% = 250g per day Total. so 125g in AM and 125g inPM

or you can break this into 4 feedings per day.

So at 1 percent we are feeding 250g per day this is 7.5kg per month(30dys).

With the same mass 3% will be 750g per day and 22.5kg per month

6.5% of 25kg would be 1.63kg per day and 48.75kg per month.

Thanks David, very valuable information.

I also read an article that stated that koi absorb more of their food at night.

So at the momment i am feeding 7 times at night but very small amounts. (Im suppose to work on 1% but im on a budget) I know some people say you should not feed at night but my koi eat much better at night than during the day. I feed at 4am, 6am, 8am,..........(10 hour gap)....... 6pm 8pm 10pm and 12pm.

Wayne
Watse siekte het jy wat die slaaploosheid veroorsaak?

Hi Jan, gelukkig het ek 'n koi feeder wat die werk vir my doen terwyl ek lekker .

Just did the calculation, mm that is a lot of food....thinking possibly to add a bit of a variety, cheaper and more expensive food, before I need to get a night job...