Fish are excellent swimmers with high swimming efficiency and perfect manoeuvring abilities. Designing a robotic fish with fish-like swimming behaviour in a dynamic environment is such a challenging task, that it requires a full understanding of hydrodynamics, fish propulsion mechanisms, and the approaches for mimicking the real fish swimming. This book is based on author's PhD thesis finished at University of Essex in 2007, which aims to develop: (i) a control architecture for autonomous control, (ii) basic fish-like swimming ability, (iii) behaviour-based intelligent control, and (iv) online learning algorithms. The Essex robotic fish has been reported widely by major media including BBC, ABC, CNN and National Geographic since 2005. Many multimedia resources can be found in the Internet.