When I was a kid Darebin Creek was considered little more than an open drain and in the areas close to Northland and the Olympic Village it was used as a dumping ground. There is now a bicycle and walking path covering most of the creek and attempts have been made to clean up weeds, remove rubbish and replant native trees. The creek was actually flowing while I was there and I did manage to find some macro invertebrates under rocks near the Plenty Road bridge, tiny crabs actually. I had no idea crabs could be found in fresh water south of the equator.
Anything living in there would have to have a high tolerance for heavy metals. Just in the spot where I was looking I found a discarded car battery.