This book is an initiative of Projeto Manuelzão to disseminate the historical information on the fishes of Rio das Velhas, the most important tributary of the Rio São Francisco basin. The monograph written by Christian Frederick Lütken in 1875, based on the material collected by Johannes Theodor Reinhardt, was almost inaccessible to the Brazilian ichthyological community since the Danish language is quite unknown within Brazil. The book consists of three chapters.
The first chapter, written by Dr. Heraldo A. Britski, outlines the historical position of Lütken's work, in connection with the work of other naturalists who came to Brazil since the early XVIII century to collect fish species to European and American Museums. Britski also updates the systematic nomenclature of the species cited, including the application of recent morphological terms in substitution to those that are not used anymore.
The second chapter constitutes the first translation of Lütken's monograph into Portuguese. Dr. Luiz Paulo R. Vaz translated the original, written in Danish (with references and citations in German, French, English and Latin), and Dr. Vicente P. Iannini translated the Latin synopsis. Lütken's work offers the first description of tens of species, at a time when not more than forty species were known for the entire São Francisco basin. It is also remarkable because, at that time, there were no intensive studies on just one river or hydrographic basin. Generally, naturalists collected material of many zoological groups through their extensive trips to the continent, covering many river basins or thousands of kilometers.
Finally, the third chapter presents a comparison between Lütken's historical work (middle XIX century) and data collected in the late XX century. Carlos Bernardo M. Alves & Paulo S. Pompeu show how the recent development and population growth could influence the present occurrence and distribution of fish species. They also discuss the perspectives for the fish fauna recovery and for its conservation.