That jumping activity could be flukes or other parasites on the gills
irritating the fish. They will jump, get a large mouth full of air, then
express it through the gills as bubbles under water trying to wash the
parasites off. Look at http://www.akca.org/ for a koi club near you and see
if they can provide microscopic evaluation to know what to treat for.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"gng" wrote in message
...
I have a 2500 gallon pond with about a dozen koi. One of them is around 5
years old, 15" to 18" long. He is constantly lifting his head above the
water as if grabbing bugs. I thought this was what he was doing, but
someone said that he most likely is going for air. I accepted that for a
minute as I will admit that he does this pretty much all the time, but
then
thought "wouldn't that make him a mammal like a whale?" I don't mean to
appear dumb - but who is right? Bugs or air?