Well if you are aware of the lagoons located in sandgate then you would probably know of the tilapia located in them in plague proportions.
However. i have now spotted a school of large size individuals in a small drainage channel that flows past deagon cricket parks, crosses board and braun streets and then into cabbage tree creek. this spot i saw them (braun st near squash centre) is usually estuarine with mangroves located on the edges but i think with all the fresh they have been washed down. pretty surprising to see them in an environment thats basically a drain!
These fish are having a massive effect on our native freshwater fish displacing most of them through competition for prey and habitat, predation and are highly aggressive. They breed fast and look after their young.
wasnt sure if this was supposed to go in fw or sw so feel free to move. cheers