On Thu, 1 Mar 2007 22:14:24 -0600, "sue" wrote:

Can anyone tell me why 4 large koi would die and 4 goldfish not?I have 8
fish in a holding tank for the winter and they all were fine and one day my
koi are dead ,no sign of disease or anything.The other smaller one are
fine.Were they getting too big?Needed more room?

I had the fish in a 100gal tank the 4 that died were -12 long the small
ones are 4-8 inches long,1000watt de-icer that kept the water nice at
45c.they didn't move around much because they are in hibernation.They were
in here since October.

Water quality would be my guess. Lack of O2, big fish die first. The only
way to know would be to have the water tested..... and depending how long
ago this happened, the cause may have dissipated by this time. ~ jan