Fish Dying, Someone Please Help!
SOS. I need some help!! I have a lot of goldfish in my pond and am not new to ponds, this one has been established for 5 years, but there has been a pond in that location since '93. Last night someone left the hose on in the pond filling it up.. They must have forgot it and never turned it off. It was running for at least 6 hours and it was overflowing... My mom and I just caught it early this morning and turned it off. This wouldn't be a problem normally except almost all of my fish died! Before this I had 19 goldfish, 2 koi, and 2 creek chubs. I now have 4 healthy goldfish left living and one goldfish still struggling to hang on. After turning off the hose, we noticed almost all of the fish floating on top, still trying to swim. My water is well water, and every other time we've used it to fill up the pond the fish have been fine..... We've never kept the hose on in there for 6 hours before. The only thing I can think of is maybe a rapid temperature change with the hose filling it up, but I've never had trouble before!
Here's my pond readings
240 Total Alkalinity
100 Total Hardness
Help someone who might know what's going on and/or who knows how to save my fishies!