Red-eared slider turtle

The red-eared slider turtle is now established in Queensland, and one was recently caught in Blackburn Lake. They have no known natural predators and prey aggressively on native fish and frogs, and reduce the food available to native predators. They can breed prolifically laying up to 70 eggs a year. The species are in the World Conservation Unions top 100 "world's worst invaders" list. What dill brought it in and why?

We seem to be heading for fewer species in larger numbers, a bit like the book trade. The weedy and aggressive survive.