I have never tried that much chlorine in my pond (despite cleaning the
deck next to it). In our aquarium, however, we have put too much
chlorine in. The fish suffered, but recovered. I suspect the key is
how badly the gills have been damaged. If the fish can get oxygen and
if it does not get infected and if it is well enough to heal, I
suspect it can make a go of it...ours did.

Jim