John,

It is hard to do this long distance, but I don't think your fish have
dropsy. These look like KOI with mirror KOI with separated scaling. Dropsy
would be a blotted body and all the scales sticking out from the body of the
fish like a pinecone that has ejected its seeds.

The parameters that your gave were OK, except for your dissolved oxygen.
KOI can deal with 2-3ppm of oxygen for awhile, but 1ppm can be lethal
especially to larger fish. It always seems that the larger fish all seem to
die off first. It is also may be compounded by the .1ppm of your nitrites.
Also you have top remember than you also probably took your oxygen test from
the water surface, where there is depth there could even be less oxygen
present. Ponds, depending on their design and ornamentation and plants
baskets can also stratify in areas even though there is circulation of
water. This low ppm of oxygen and higher temps may have brought on your
situation.

You should strive for at least 5ppm for oxygen concentration.

Unfortunately this could also have been brought on by the addition of your
new fish, and something that they carried that was stimulated by the low DO.
In my opinion 2 weeks is not enough time to quarantine. I quarantine my
fish for 4 weeks, of which one week of that time there are given a treatment
according to the label of the fish med Melafix. The next ten days they are
given an full spectrum antibiotic. After the ten days I leave them to swim
in their new surrounds to finish out the month. Fish diseases can be
carried and then brought on by a condition, and this may be what happened in
your case in addition to the low DO situation.

In any event, get your DO up some more.

HTH

Tom L.L.
"John" wrote in message
...
Thanks to all for your help.

Unfortunately I'm still losing fish, another one died tonight.

I was particularly concerned about the theory that it could be dropsy.
from
what I read this is incurable. Would it then affect all the fish in the
pond? Is there anything I can do?

I did add three new fish about a month ago, but that was after a two week
quarantine period and all three seemed OK, although two have now died.

Thanks again

Any further help would be appreciated.