Five years of work, thousand river sections studied and traveled 60,000 km, giving an idea of ​​the effort to obtain the information in this book. We doubt that some Iberian river has been studied with such intensity and such a relatively short term. This has made it possible to have a very detailed picture of the distribution and conservation status of freshwater fishes in the main Andalusian basin of the Guadalquivir. But it has also allowed also know the problems of preservation, destruction of habitat, the presence of exotic species, fragmentation and degradation dominant disturbances. Now, it is up to the managers to respond to the problems identified. Finally, this comprehensive work, not only detect problems but also locate the areas that still have good communities of indigenous fish. Some of these areas in different geographic areas of the river basin could become reserves to ensure the future survival of these unique species. The work is aimed at managers and conservationists fundamentally, but we believe it can be very useful for the general public awareness which is more than necessary to achieve the objectives of conservation.