Not exactly a return of a fish species, but the Barramundi that was caught in the Coomera River last year was pretty odd. Even though it most likely escaped from the impoundment near there during heavy rains, it was still surprising.
I've noticed an increase in baitfish in Coombabah Creek in the last few weeks though. Don't know if it's seasonal, but mullet and herring seemed to be everywhere.
Cheers,
Kaidon