Hi,

.../I suggest that it would be very worthwhile investigating native fish as an option. You can contact the Australia New Guinea Fishes Association for some more info. 

They have a database to find fish indigenous to your local area and you could contact the association for info about obtaining and caring for fish.

Here's a link to their webpage:
www.angfa.org.au/intro.html

Cheers,
Sandy Eager

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