One other thing I need to do is to drag all of the dieing vegetation out since that looks like one of the dominoes that lead to this situation. It was pond weeds that came in on the wind, as I have seen them on other ponds in my neighborhood. They added cover for the fish so I left them in but eventually they were covering 20 % of the surface area so I started raking some of them out. Then the hot weather came in and started killing them and that probably led to this. They will have to go and not be allowed back.

It's time for me to hit the sack so I can get up early and rake pond weeds and casualties. I hope the buzzards have an early breakfast.

Thanks for your advice Bruce.

Richard