I found (with the help of Jeff Johnson of the Qld Museum), that is a Crested Oyster-goby (Cryptocentroides gobioides). They (like the similar Oyster Blenny - Omobranchus anolius) are found in oyster and mussel beds along the Queensland and to the central NSW coasts, and they grow to 120mm. The body of the Oyster-goby is generally olive-green, and have distinct irregular vertical bands of red-brown, and electric blue which alternate, and become longer in the lower body. The head has electric blue and dark spots, and the dorsal fin has black streaks. The dorsal and upper caudal fins have red-brown spots, and the fins have margins of red-brown. They live in the intertidal zone, and this one was found under rocks at low tide. Caught Lukus Martin at Evans Head looking under rocks covered in oysters at low tide - NSW