We are interested in the mechanics, energetics and control of how fish swim in natural flow conditions. Fishes routinely encounter unsteady flows in nature, such as when schooling or swimming behind a rock in a stream. Our approach is to expose fish to unsteady flows found in the characterized wakes of simple objects such as cylinders. By systematically altering vortex size, spacing, and shedding frequency, we have found that fish can actually extract energy from their environment and save energy by swimming in turbulent flows. Our current work looks to understand the role of body shape, flexibility and kinematics in exploiting flows under more complex hydrodynamic habitats.