That's an attribute of chloramine, not fluoride. Chloramine is used as a disinfectant. It's a compound comprised of chlorine and ammonia, typically in a 4 to 1 ratio. Very harmful to aquatic life but not harmful to humans or their pets.
You're most likely adding sodium thiosulfate to neutralize it.
Oh stop letting facts get in the way of a good rant. That’s not the way things are done on FR.
Very interesting. I know they sent a letter around saying the town was adding more fluoride but I don’t think they mentioned Chloramine. I use some additive if I have to use hose water but I don’t know what it is. My koi dealer suggested something & I went with that. Since I changed to a very heavy duty liner things have been better too. Some of those koi I lost were so big. We raised them from babies & we could hand feed them.