Thanks for the response Peter. Nice web site too! It looks like you've spent a lot of time observing the behavior of baitfish and the feeding patterns of predatory fish. Here's a little more info so you (and others) can apply your knowledge to my situation.
I plan to fish this fly in a small river (20' to 40' wide) with slow flowing, somewhat murky water. It has a mud bottom with some grass and lots of tree limbs. There is plenty of overhanging brush along the shore, and the deep sides of the river bends have steep, almost vertical mud banks. Virtually every type of fish that swims in Berkshire County can be caught in this section of river, but my primary targets are largemouth bass and pike. And it's absolutely loaded with yellow perch. I have observed the perch while they are grubbing for food on the bottom. They move slowly along with their noses on the bottom and bodies tilted up at an angle. When you spook them they slide out sideways into deeper water, staying right along the bottom. This is the behavior I am trying to imitate with the fly. My thought was to drag the fly slowly along the bottom and occasionally let it swing laterally in the current. It's more of creeping/sliding action than a jigging action. I want the fly to stay on or near the bottom even if I swing it into deeper water, hence the need for a weighted fly. The fly is not intended to imitate a crippled or disoriented bait fish because there are no rough currents that would cause such a thing to happen. It is supposed to be a feeding baitfish that carelessly moves into the predators' ambush zones.
I'll do some more experimenting and see what I can come up with. All further comments and suggestions are welcome.