A dark banded weed-feeding fish of estuaries and shallow rocky shores, usually in schools of a dozen or more.
To about 71 cm, though the Australian Museum gives about 60; common at 35. Evenly arched above and below with a small mouth and eye and a large tail, bluish-grey at sea and darker grey-brown in estuaries, with eleven or twelve thin tapering vertical bars fading to silver below.
Those bars separate it from the rock blackfish, which is uniformly blue-black.
Nought to twenty metres in estuaries, mangroves and on inshore rocky reef. It is a herbivore and a strong schooler, grazing algae off rock and off floating material. Larvae use estuarine seagrass and juveniles mangrove creeks.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.