I've done a fair bit of googling and actually found a very nice site that listed mammals, birds, and herps that are introduced down here, whether they're known to be breeding, and the counties they've been found in. I'm looking for something similar with fish, or even as simple as a list of fish you've seen/collected down here. Basically I want to set up an outdoor pond and stock it with fish that already occur down here, as I know the climate should be OK for them.