Thanks for the support and suggestions. FYI half the fish seem to have survived intact, including 2 angelfish, 5 clown loaches and half the cardinal tetras. Three denison barbs and a dozen penguin tetras bought the farm. No long term ill effects that I can see except the fish are not eating much, probably still in mourning from all the dead bodies. At least I know what it is now, for a while there I was considering giving up and getting plastic fish!!!!!!!