Whilst there are bull sharks in Sydney, fear not, you are highly unlikely to ever see one. It is understood that they come into the Sydney harbour and swim up the Parramatta River to breed. The juveniles stay in the harbour until they are big enough to venture out to the sea.
The video and photos uploaded here are of bull sharks seen in Fiji. I am hoping to see one in Sydney, although I will certainly keep my distance as they are large powerful sharks.