The poison they're using, rotenone, is more along the lines of an insecticide which kills fish, but is short lived. So thankfully, most other wildlife will survive it as long as they don't breathe under water. This is how they tend to get away with it. Frankly I'm amazed that Australian government hasn't been tried for environmental terrorism yet, but then how many more governments are at it too?

As you were saying to @realtreebivvy, most Aussies have been indoctrinated to hate carp (among other things) so anything from us probably comes in the region of conspiracy nuts.