In this talk, we will address following issues:

Firstly, the hydrodynamics principles of fish swimming, such as the vortex dynamics principles of speed control, direction control and energy-saving of maneuver swimming of fish school will be discussed.

Secondly, we will discuss the technique of flow control with moving wavy wall, and the application of this technique to the fish swimming, in order to completely eliminate vortical wakes of fish swimming.

Thirdly, we will show the result of topology optimization of caudal fin, which is much better than the lunate caudal fin of shark, and discuss the physics behind the optimization process and results.

These results are applicable in the design of bionic fish.