Koi are very hardy fish and they actually can deal with an ammonia spike quite well, IF they have the water capacity.
Koi also grow very quickly, on a varied diet mine grew 1"+ per month.
I don't think 10 gallons is not going to cut it; donate them or they will also parish in that small tank.
Koi also grow very quickly, on a varied diet mine grew 1"+ per month.
I don't think 10 gallons is not going to cut it; donate them or they will also parish in that small tank.