the key is "the larger" fish died. this is almost always a sign of
problems with enough oxygen. oxygen problems occur as water temps
increase. they die in the early morning hours. at any time you see
fish at the surface "piping".
otherwise, it could be a disease attacking the gills. it could be
toxins, so do take the board out of the water and only use plain pine
in the water. you dont have any yew trees or bushes around do you?
yew is extremely toxic, sometimes the berries drop into the water.

the other think it might be is infection of egg bound female fish. you
would need to do a necropsy and see if the egg sacks are yellow... any
color but clear/white.
http://weloveteaching.com/puregold/d...e/gf_anat.html
Ingrid




On Sat, 23 Jun 2007 11:24:08 +0100, "Carole"
wrote:
I have a mature pond about 8 years old, 800 gallons, about 50 goldfish
ranging from tiny tiddlers to about 5" long, plus one really big ghost koi
about 18" long. I have all the usual filtration, waterfall and oxygenating
plants, UV light, water is nice and clean and clear and always has been. I
feed the fish about every couple of days - if they get too much they get
frisky.

Big problem - In the last week I've found 3 of the larger goldfish just
floating dead in the water. They have no signs of any disease and look
perfectly OK, just dead.