Fishes of the World
Fishes of the World by Joseph S. Nelson is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the 30,000-plus fish species known to science.
The book begins with a general overview of ichthyology, although it is not self-contained. After a short section on Chordata and non-fish taxa, the work lists all known fish families in a systematic fashion. Each family gets at least one paragraph, and usually a body outline drawing; large families have subfamilies and tribes described as well. Notable genera and species are mentioned, while the book generally does not deal with the species-level diversity. The complexities of the higher taxa are described succinctly, with many references for difficult points. The book does not involve color illustrations.
The fourth edition was the first to incorporate the wide use of DNA analysis, revising many earlier classifications.
The first edition appeared in 1976, the second in 1984, the third in 1994 (John Wiley & Sons, ISBN 0-471-54713-1), the fourth in March 2006 (ISBN 0-471-25031-7), and the fifth in April 2016 (ISBN 9781118342336).