Im no expert Miggy only been keeping fish myself just under a year but like many you learn the hard way and through mistakes made, but I have done a lot of reading over the last year
mainly tropical though, goldfish are cold water so have different needs
another story has come to mind
I have a siamese fighter (betta) and when I first got one I was advised I only need a small tank as they live in puddles and rice paddies of Thailand and are happy to live in tap water
after some research I found they do live in rice paddies but these run for miles lol so although the info was correct he played with words and although they can live in hardy conditions they cant live in tap water it still needs to be treated but dont need to be oxygenated
this is what shops sell for Bettas
no room to swim at all