It's been my experience that when the peacock bass turn on and start feeding they will pretty much hit any fly. I do have a favorite.
My first choice is a small white streamer fly tied on a "keel" hook. I like the keel hook because it seems to be fairly weedless. I like white, because I can see it. (yellow, pink, chartreuse, orange, or combinations of those colors work too)
I think a little iridescent flash-a-boo in the fly helps. (the shad in the lake are small, 1 to 3 inches, and their scales have a pearl/aqua sheen to them)
Here are 3 flys I just got from Nervous Water Fly Shop.
http://www.nervouswaterhawaii.com/guideinfo.htm
Two streamers (Maltese Minnows) and a fly that looks like one of the live baits from the pet store. (Mollie... feeder fish)
The way we fish for peacock bass is to follow the shoreline, casting the fly in tight to the edge and stripping it rapidly back out to the boat. (Cast right into the grass and brush.... now you see why I like weedless flys and lures.) The little fish that the peacock bass eat are tight against the shore.... the peacock bass are always on the move patrolling the shoreline..... just keep moving till you find the fish.
I like a 5wt or 6wt flyrod... weight forward floating line and a 5 to 7 foot tapered leader. (6# or 12# pound test.... peacock bass are NOT leader shy) Chris like a 3 to 4 foot leader and strips the fly all the way back out to the boat... (you never know when or where the big one will strike) He wants that fly in the water as long as possable.