Where can I get metronidazole in AU?

It's now apparent that my big oscar seems to have a hexamita infection
- single long strand of white membranous looking faeces, been there for
24 hours.

I've seen it written about the place that you should use metranidazole
for this. Problem is, it doesn't seem to be such a common finding in
Pet/fish stockists in Australia. It's only on ebay from overseas
sellers, and I'm pretty sure it's illegal to import medication from
overseas.

Is there something else that will work? As I don't really feel like
pretending that I have a gastric ulcer so I can get some prescribed to
me!