Help required - fish dying

"John" wrote in
message
...
Over the last weekend I have lost 7 koi and
am at a loss as to why. A few
days ago the koi in my pond generally
stopped eating, having previously been
ravenous feeders. I tested the water and
all tests proved "normal" (ph 8.0,
nitrites 0.1, chlorine 0, ammonia 0) except
for oxygen which had dropped to
less than 1ppm. I run with 2 filters
dropping approximately 1500 gallons
per hour, two spitters and a fountain
running at 250 gallons per hour and
can not understand the low reading. I
immediately added an air pump with 4
air stones and continue to run that as
well, although the oxygen reading has
only gone up to 2ppm today.

The fish that have died have all isolated
themselves from the others, and
been very slow moving, although do evade my
attempts to net them, right
until they are nearly dead. I have noticed
that all the dead fish had a
heavy mucus coating on their skin making
them extremely slimy, and that some
of their scales had become very prominent
(I have posted some pictures of my
latest loss on
http://deadfish.mysite.freeserve.com/).

My pond is approximately 2250 gallons with
koi, goldfish and orfe. This
only seems to be affecting the koi though.
I am in the UK and temperatures
have been very high recently, with the
water temp in the pond reaching about
24 C.

Any help as to how to help my remaining
fish, as well as how to improve the
oxygen level in the pond would be greatly
appreciated.

TIA

John,

Have you tried koivet.com?
They have a lot of info which might be
helpful to you.

I am sorry for your loss.

Best wishes,

Jeannette