Textbook in PDF format This book describes the process of making the major breakthrough in the study of animal self-awareness using fish. The discovery led by the author’s team, proving the mirror self-recognition ability of fish, is vividly documented as they share the process of making, testing and verifying hypotheses and developing further hypotheses. The clear experimental results demonstrate the remarkable self-awareness in animals, overturning the conventional view and providing a key to understanding the origin of human self-awareness