Sorry, hope most of your fish pull through!! One thing to note for everyone when the temp. drops in the fish tank, observe the fish that appear to be dead very, very carefully for any sign of light breathing. When the water gets down that low, they loose color and kind of go into a hibernation mode until the water temperature rises again. Even if you net them in this state, they will not move a bit. Just watch for the very shallow breathing.
This is so true, and something I had been thinking about as most of the fish recovered. I think the temp in my tank got down to 40F or lower, and there were many fish that were upside down, appeared not breathing etc. I even poked my rubberlip pleco with a net to be sure he was dead, then later noticed he had moved, and is now back in his cave as if nothing had happened. My angel pair are back in their breeding behavior, and my GBR is sniffing all around the tank for food as if nothing happened.
The black neons and cories appeared as though they were not bothered at all though.