Fish have been hitting this fly for years. The Pheasant Tail Nymph remains one of the top mayfly nymph imitations around, and it can be fished in running or still water. It has a distinctive ringneck pheasant tail barb. Per 12. Sizes: 12, 14, 16. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Fly Assortments.