Daryl:
None of our ducks eat fish as their main diet afaik, but we have cormorants, anhingas, and grebes, none of which are legal game birds in northern Australia.
Not very appetizing either I would venture!

Locally, the most sought-after is the Pacific Black Duck or "blackie", a bigger bird that is easier to pluck and very tasty, but they have been conspicuous by their absence from my usual haunts so far this year.