The koi are just getting used to the new pond. The pond is too small for koi.
You need 1000 gallons for the first koi and then over 100 gallons for each
other one.....so for your 2 kooi you need at least 1100 gallons. Koi also need
some areas of the pond that are at least 3 feet deep . They will do fine now,
and when they grow larger they will die because of the water quality the small
pond will have. Sorry Jerri

http://www.fringeweb.com/Ponds/JerrisPond