high amonia

[Big Frank]

pond 1200 gallons 4 x 20" and 1 x 15" Koi (Ghost or metalic, I dont know the difference) also 6 small goldfish. 4 bay filter, waterfall.

The pond is now 6 weeks old and after some early issues with bacteria bloom the water is nice and clear and the fish look good. But tonight they seem to lost their appetite. I mean they have eaten 75% of their food but they are not feeding with there usual vigour. I have tested the water and:

PH OK
Nitrite 0.25
amonia 0.3

I am changing 20% of the eater, should I stop feeding them.?

why has this happened? are they overfed?

 

[rdk]

Do you do water changes ? This is the time my new pond amonia went sky high without weekly water changes of 30 %. RDK

 

[PS3]

do larger water changes 2 times a week and feed the fish less
if the pond is six weeks old the bio filter might be starting to kick in