"Richard C. Eberhardt" wrote in message ...

Well, all the koi are dead now: the pretty 12" ones I had for six
years and
the 3 new ones added this summer. They seemed to die one at a time, from
largest to smallest animal.

3) Added a mosquito magnet about a month ago. This burns propane to create
CO2. This was about 15 feet from the pond at a lower level than the lip of
the pond. (Note: this is about 20 feet from the old pond which is full of
goldfish and has not had these problems).
3) The CO2 plume emitted by the mosquito magnet created a CO2 pool over the
pond, resulting in a low oxygen situation. The fish were gradually poisoned
by the gas. The larger the respiration system, the faster the succumb.

Any Ideas would be appreciated, especially advice on how to safely start
over.


Rich, I believe the fish were poisoned and died real similar to your
thoughts listed above. As a wildlife biologist, i have seen poisoned
streams etc..where the largest critters died first. Almost always due
to poisoning of some kind, pesticides, herbicides, etc..

In your case, the pesticide killing all the bugs prolly coated the
water surface and formed an almost invisible layer locking out oxygen
exchange etc.. Also, with the CO2 plume that heavy, no doubt many
"poisoned" bugs fell into the pond and were fed upon.

Also, herbicides placed on grass and lawns to kill weeds etc. very
common killers of critters, altho usually the smallest critters die
first in this regard.

my 2 c

Montanan