Mostly Argyrosomus japonicus (=A. antarcticus) but also a few Chrysophrys auratus, a few Siganus sp. (probably S. canaliculatus or S. fuscescens), a single Lates calcarifer in the foreground and a headless Trachinotus sp. in upper left corner.
I don't know the scientific names, but know a few of the common ones.
Front is a Barramundi, with a snapper behind him. Right in the centre I can make out a couple of Mulloway, and there are 2 more snapper swimming in towards the centre from the right. Top left swimming away is a Trevally of some sort possibly a giant Trevally.
It was the mass of fish in the middle that were unidentified - one very large school that stayed together and moved together (similar to the way a ball of striped catfish move). I'm happy with your identification of Mulloway (Argyrosomus japonicus). The headless fish, looking at other slides I took, is probably the Small-spotted Dart (Trachinotus bailloni).
Looking at that mass of fish in the centre, I think they are all Mulloway, but the description of them all staying together and moving in a ball does not sound like what I thought Mulloway did, but I don't know what else they could be.
