I have fished for leichardti before, saw a local fisho land a monster at 117cm long in a stocked dam. Never fished for Murray Cod, although I know of places where they can be caught.
Bumble Bee groupers? Not sure if its the same fish, but I have caught what we call Queensland Grouper (Epinephelus lanceolatus) over here. Is this the same fish? Not sure, since the ones we caught were all in saltwater estuaries, and were at least 2 ft long; still babies for the species and having very different coloration from the adults.
The bumble bee groupers I see in MFK are kept in fresh, and mostly small.
Here's pics of a juvenile Queensland grouper. Are they BBG? By the way, these guys pull like steamtrains! Not so much speed like tarpon, but way up there in terms of torque.