Mollies aren't a problem in most parts of Australia. Platies and swordtails are and so are some of the South American cichlids. You can catch oscars and texas in Queensland, and we have some lovely looking variatus platies and green swordtails around Perth.
I would much rather have mollies in our rivers instead of Gambusia.
Why are fish illegal in some countries and not others?
stupid governments, grrr.
We have some really dumb laws in Australia regarding aquarium fishes. The latest one to appear is you are only allowed to keep fish that are native to the state you live in. Basically it will mean I am only allowed to keep fish that naturally occur in Western Australia. This gives me about 12 species of fish I can keep under this law. Some of which I won't be able to keep because they are only found in national parks and you aren't allowed to collect fish in national parks.
The Northern Territory has actually made this a law and the fishkeepers up there are only allowed to keep fish from the NT. All the other states in Australia are still thinking about introducing this law. If they do make this law then fishkeeping as we know it will change completely. And petshops, will go belly up all over the country.
Another stupid law we have here is you can bring in male Paradise fish but not females. And the fish must be over 3inches long. However, no one at AQIS (Australian Quarantine & Inspection Services) knows how to sex paradise fish.
We had a similar law a couple of years ago where we were allowed to bring in Glossolepis incisus, but only males. After 12 months or so they banned G. incisus again and we are no longer allowed to bring them in.
On the subject of rainbowfish, we are not allowed to bring rainbowfish into Australia even tho they naturally occur here and most species are already here. The government's reasoning for this is to stop the introduction of species that could get into our natural waterways and breed with, or outbreed our native species.
Now I can understand that to some degree, but if the fish are already here, and they aren't cheap to buy, why would anyone travel hundreds or even thousands of kilometres just to let them go. And if anyone was going to let them go, surely they would have done it by now.
Another stupid law is with keeping Koi carp. You can keep them in the southern half of WA but not in the northern half. The government is worried the fish will get out and survive in the wild. They will survive in the wild (and are already there) in the southern half of WA. Now they ban Koi carp from some parts of Australia but not common goldfish. Yet you can find goldfish in half the rivers around the country. Another issue with goldfish is any that get brought into Australia must be accompanied with a certificate from a vet stating the fish are free of goldfish ulcer disease (GUD). However, Australia's largest goldfish farm has GUD in its ponds and supplies thousands of diseased fish to every shop in the country.
Plecostomus catfish are another one. You can import two big species, common pleco and gibbiceps, but you can't bring in any small species. The people making the laws are concerned the smaller species will cause problems. I would think an 18inch pleco would do more damage than a 3inch peckoltia.
A final one is to do with marine cleaner shrimp. We aren't allowed to bring marine cleaner shrimp into the country even tho they naturally occur around the northern half of the coast. Local collectors get them from our waters and our waters are often filled with larvae swept in by the tropical currents from Indonesia. Yet they aren't allowed in from Indonesia even tho they are the same thing and potentially form the same parents.