black is almost always toxic water, like if they sat down on mulm that
had a lot of H2S coming out. is the pond clean on the bottom?
black spots are a sign of disease transmitted by snails.
If you got em right away take a look at the gills. dark gills = toxic
water.
Ingrid

On Thu, 10 May 2007 06:32:32 CST, John
wrote:

Just found 2 dead goldfish in my pond - black discolouring on their
undersides.
Can anyone help diagnose and say whether I need to do anything to the
pond please?