Back in South Africa I put some goldfish in a pond I had out front of my house it was about 300gal and they thrived, I got a breading pair and they had many generations of babies and grew to a foot in length (I think they were commit goldfish.) The thing is I never used treated to water and used tap water, could goldfish be less susceptible to chlorine? or was my water quality very good? (I heard that my city had some of the best tap water in the world) I never really tested it for chlorine though but still treated the water going into my tanks ofc.