Wish I could be of help. We stayed up there at a house at Boreen point one weekend a couple of years ago. Hire a boat and went every where up to and a little past Harry's hut (is that what it's called?). Had some fun with some cat fish, but it was a VERY slow day. On our way back to the boat hire, we 'found' a spot (someone else was fishing nearby), and had a shot there for a short while and caught heaps of flathead. But I'd have no hope of telling you where it is/was. Probably about 5-10min north of the boat hire place?
Anyway, there are fish about there, but from our one day of fishing, they seemed very localised.
I'm sure there's plenty of people on here that can help you out!