Many species of fish feed on shrimp. The trick is to approximate the color of the bottom with the general color of your fly. Most bottom dwelling animals that live on flats or coral reefs are able to change color to match their surroundings. This fly is best over darker bottoms.
The tan colored fly is proven for use over light colored bottoms. Bonefish love both colors of the EP Spawning Shrimp. Both colors are extremely productive in the Bahamas and Belize.