Scolopsis bilineata (Two-line Monocle Bream)

https://bie.ala.org.au/species/https://biodiversity.org.au/afd/taxa/4aaa9ebd-8944-4f57-b625-738d67980862

https://fishesofaustralia.net.au/home/species/618

From Fishes of Australia: 

Body with a blacked-edged white stripe curving upwards from below eye to the middle of the dorsal-fin base. Juveniles - upper half of body black with two yellow stripes, midsides with a broad white indistinct stripe, anal fin with a black marking.

Juveniles mimic the Linespot Fangblenny, Meiacanthus grammistes which has venomous fangs.