Bruce, just an obserbvation, we also have had a massive vegetation die off here in the month of July through herbicide applications. We havn't had any fish deaths from it and I think the reason why is that the majority of nutirents in our pond have been tied up in the vegetation preventing an algea bloom. We didn't get an algea bloom going until after the weeds died and the nuturients became available (aka a herbicide induced algea bloom). It sounds like your pond had a good algea bloom going on when the pond weeds died off naturally. So my thoughts are that a large scale weed die off when a good algea bloom is present is probably more likely to cause a fish kill than a weed die off when there is almost no algea bloom present, thoughts?