I am a committee member of safwaa (South Australian Fresh Water Anglers Association), the clubs title is a bit deceiving as our main focus is on 25 dams that we stock with fish (Murray Cod, Golden Perch, Silver Perch, Catfish, Rainbow and Brown Trout). These dams vary from barren small farmers dams to massive property owner dams with dead trees and lots of snags, the club knows for sure the Catfish breed in the dams (you can see them making their nests and later the babies swimming around) but we have no evidence that any other native breeds in them. All our dams are teaming with feed / bait fish, these and the shrimp do breed prolifically in our dams.
Perhaps in a warmer climate and even better conditions natives could breed but even if fish in our dams did breed there is a good chance the Murray Cod would eat them. We have some very large Cod in our dams, recently a new member got one 30 - 40 lb and we know some of our dams have unstoppable ones in their (they have been hooked but not landed).
All Trout will die in around 3-4 years if they can't breed, which is next to impossible in 99% of any dams.
Steve