Compared to mammals, fish are often underestimated and dismissed as less complex organisms. To refute this hasty conclusion, Horst Bleckmann introduces readers to the highly developed cognitive abilities of fish. Many people might not know that fish are the largest group of all vertebrates, with about 30,000 species, and that they colonize all aquatic habitats. For this immense feat, they have evolved a variety of highly specialized sensory systems and behaviors. According to recent research, fish also possess not only extremely sophisticated sensory organs, but also highly developed central nervous systems that are similar in basic structure to the brains of mammals. Readers will be immersed in a fascinating world as they learn about the different sensory systems of fish. A concluding chapter additionally covers the global threat to fish from water pollution, cross-building in flowing waters, and the fishing industry.