Tenkara flies can be designed to float, sink, or have neutral buoyancy. Whether the fly floats or sinks will depend on the specific pattern and how it is tied. The buoyancy of the fly you choose will depend on your fishing conditions and the behavior of the fish you're targeting as the fly needs to mimic the behavior of insects either above or below the water’s surface. Observing the behavior of the fish and adapting your fly choice and presentation accordingly will help increase your chances of success in tenkara fishing.