The Mysis Shrimp is a superb imitation of the commonly found freshwater shrimp. Lots of anglers throughout the Rocky Mountains have fished a mysis shrimp imitation on tailwaters and have had great success. Often time anglers will fish a double mysis shrimp rig in different sizes, this has been known to be very effective. You can fish the mysis shrimp yearlong with success. Have a few of these flies in your fly box if you head to the Rockies.