Hi and welcome rickciudad. I'm in northern NSW so can't help with advice about Sydney suppliers.
I just responded to your other post seeking jade perch suppliers in Sydney... but, seeing you're just starting out, I'll add some comments here. Forgive me if following is already known to you!
I'm very happy with my jade perch. They grow fast and are relatively hardy - survived despite me being an absolute beginner. But they don't like the water temperature below about 20. They start to eat less and get very sluggish below about 18. Some say they die below about 15 but I have a mate nearby who swears his are still alive despite his overnight temperatures dropping to 13 fairly regularly.
Even up here, I have to heat my jade perch tank... though only for about 3 months and I have the tank and growbed very well insulated. You might be up for a big power bill down your way.
If you want native fish, think about silver perch. They have a much wider temperature tolerance and were said to be a good beginners fish when I was starting out. I got 50 fingerlings to start with, expecting to lose a lot of them as I learned aquaponics. But they all survived so I had to give most of them away. They won't need heating and they taste great smoked. Main downside is that they grow relatively slowly - I think average about 18/12 to get to plate size - whatever that means
Maybe some Sydney based forum members have more relevant experience.
Good luck.