Murray cod are recorded in the river with high confidence, and so are golden perch. Silver perch are recorded too, at medium confidence. All three are native fish that eat what the river gives them: small fish, shrimp and yabbies, and whatever falls in off the bank.
The small natives in the river (Australian smelt, Murray River rainbowfish, hardyheads, gudgeons) are the forage. A dark, slim streamer stripped slowly is a fair imitation of any of them. European carp are recorded here too, and Eastern gambusia, a small introduced fish.
The rest of the fly box is a guide’s judgement. Carry a few big streamers in black, olive and dark red, a couple of large hopper or foam patterns for the surface, and some weighted nymphs for the perch.