Members of the family Cyprinidae dominate most of the aquatic habitats of Europe, from eutrophic warm water ponds to mountain lakes. The family comprises generalists and specialists, herbivorous, planktovorous and even one piscivorous species; slow-moving grazers as well as fast-swimming inhabitants of the pelagial of lakes. Due to their diversity and abundance, cyprinids play key roles in every ecosystem in which they occur. Being of little economic importance, however, the family has for the most part failed to arouse keen scientific interest. With the aim of drawing attention to this situation, and to encourage further research, a symposium was held in Salzburg, Austria. Experts from all fields of biology discussed ecological, morphological and physiological aspects of the lives of cyprinids. The publication of this collection of keynote contributions to the symposium documents the value of the comparative approach in biology. The structural and functional patterns which emerge provide hints regarding the evolutionary processes underlying the diversification and specialization of a family which, from the ecological viewpoint, is one of the most important of the freshwater fish of the entire world.