It begins with a general overview of ichthyology, although it is not a self-contained introduction, then after a short section on Chordata and non-fish taxa, the work gets down to the business of listing all the fish in a top-down fashion. Each family gets at least a paragraph, and usually a body outline drawing; large families will have subfamilies and tribes described as well. Genera and species are mentioned if they are notable, while the complexities of the higher taxa are described succinctly, with many references to the literature for difficult points.
The third edition predates the wide use of DNA analysis in taxonomy, and much of its classification will likely be revised.
The first edition appeared in 1976, the second in 1984, and the third in 1994 (John Wiley & Sons, ISBN 0471547131).