Probably 2 or so inches long shallow water. Was especially still and kind of hanging on the bottom a bit not really active at all although it did eventually move on.
Young-of-year Macquarie perch would be my take, based on location and size. Its not a galaxias, trout, Gambusia, goldfish or weatherloach so that doesn't leave many options!
Oh great! When I was going through the photos people have put up that was kind of what I was thinking but the scale was so different given the other was an adult I really had no confidence it would be that.