The Kaufman stone has been catching fish for a long time. This pattern does a great job of mimicking all varieties of stoneflies when used in the proper size. You can’t go wrong by putting a few into your fly box – just in case.. Size 2-4 are great for fishing the salmonfly hatch, while size 6 makes for a versatile stonefly size for year round fishing. Stonefly nymphs are pretty much always present in the river and they are sought after by big trout.