I noticed that it is 90% vertical shoreline. Does it have any water in the 2 - 3 foot range? If it does, you could put out some bedding matts like the minnow farmers use for the minnows to spawn on. The area would have to be fenced off so adult fish(bass, bluegill and crappie) can't get into it. It doesn't take a whole lot of spawning to get a lot of minnows. I have access to some bedding matts if you'd like to try it. Nimrod is right. If the water is gin clear it needs to be fertilized to create an algae bloom in the water so the shiner minnows have something to eat. As far as the green slime on the rocks is concerned, you could put a few grass carp in. Not many. No more than 10, at most. It will take time for them to clean up all the slimy stuff. Be glad to assist if I can.