yeah well.... fish in tanks that don't get many water changes usually don't thrive and don't remain in good health... so for the long run: it was prolly not a good idea to throw in chemicals and change it every 6 months.. especially goldfish that are the no.1 Amonia and waste creaters..
but oh well It was, as you said, several years ago
I used to have ryukin goldfish (2) in a 2.5 gl tank because none of the shops told me that it was unhealthy. I lost many good fishies that way. So now I'm kinda water paranoid with my fish. Lucky them.
I made the mistake of not really remembering the name of 'em, just that they're platies. But oh so adorable.