Hey Decka,
Depends on where you fish mate. I'd expect the inflows to be low on oxygen, high silt and cool water but the dam fringes and freshly flooded grass would be less affected.
Some readings I took with a dissolved oxygen probe yesterday on Awoonga support this.
Awoonga fringes are fishing very well, but inflows are colder and do not seem to be supporting life.
Use your eyes and ears on this one, if there is bait flicking around, Barra will be there!
In regards to Barra having to eat, yes they do but they can also support themselves easily on reserves as required.
Small fish will be readily more hungry as they carry less body mass, those big metreys have plenty to keep 'em low key for extended preiods of time.
I'd be getting amongst the fishing as soon as you can, who knows what tommorow will bring?
Cheers and good luck
Jas