okay golden perch grow way to big. basically if you want freshwater:
7xAustralian Bass.for a 7 foot 6 for a 6foot.
1x Jardini.
1x Silver Perch.
3x Salmon tail cats.
1x Flathead goby.
Basically you can keep toxotes chaterus in freshwater but they would not grow big enough. You can keep MJ in freshwater but would eat everything. As much as a pleco isnt australian there is no Large australian algae/bottom feeder. i would personally add 1-2 large plecos.
If you wanted a solitary tank you can have:
either
1x MJ
or
1x One grunter. there are many different grunters. pm Gruntaz for info. he know lots about em.
If you wanted a Brackish tank:
Either:
8xSilver scat
8x Mono
5x Toxotes jaculator
5xToxotes Chaterus.
Or:
3x Bream
3x Tarwhine
1x Flathead goby
4x Aussie Bass
6x Whiting
1x Flathead sandy,dusky other type of flatheaad.
Oh and you can keep native crays in freshwater or saltwater. buy them as feeders and grow them up.if you do change them from fresh to brackish do it over a period of a week.
Also a good tank size is 7footx30inch widex30inch high. shame you dont live in bribane i could get you the glass tank for 800Au