I have live-captured some
Gambusia holbrooki here in the southeast US. Pond edges. They are too small to attract raccoon and oppossum, but are very efficient at eating mosquito larvae. Goldfish will too, but they are more attractive to predators, and produce a lot more waste that necessitates cleaning the pond or tank more.
My gambusia had a natural planted tank indoors with a slow bubbler, but my ex introduced them to his backyard manmade still pond on my advice. They were successful and entertaining there, maintaining a steady visible population on our year round mosquito production.
I see from Wikipedia, not always the best source, that
Gambusia holbrooki or mosquitofish are now invasive in parts of Australia. The same wiki entry states that Australia does have native species of small fish that eat mosquito larvae.
Eastern mosquitofish were introduced to Australia to control mosquitoes, when in reality various small Australian native fish were already keeping mosquitoes to a minimal level.[citation needed]
They are aggressive, fin-nipping harassers of other fish and pose a serious threat to native Australian fish and aquatic fauna. Negative impacts on rainbowfish species and at least one frog species have been documented. Several rainbowfish populations appear to have become extinct due to the impacts of introduced Gambusia.
I only searched for a few minutes but did not find just what species you may have that would be better. Dragonflies and frogs are two other larvae predators that might work for you. I described the gambusia more for an example of what works for me here. If I were suddenly transplanted to Australia, I'd look for similar niche species.
