Hi, Aussie posters..
I live in Melbourne (near Coburg) and recently my brother in law (who kept a wide range of tropical and marine fish successfully for many years) told me he had a lot of trouble keeping his bettas healthy until his LFS advised a water additive to fix an issue with Melbourne water.
Problem is, this was a long time ago and he can't recall what it was, only that it possibly had to do with mineral content. He said that once he started using the additive, he never had another problem with fungus/fin rot again.
I'm really scrupulous with water changes, and both my male bettas have had severe fin rot issues that don't respond well to treatment. Could it be a local water issue contributing to this? Any Melbourne folks know something about it?