As a previous reviewer noted, the editorial review is incorrect -- this is a book about freshwater angelfish, not reef-dwelling saltwater angelfish. Whoever submitted the editorial review is a doofus, but that shouldn't be held against the book or its author.
For a small, inexpensive book Angelfish: Everything About... provides a tremendous amount of information.
The sections I found most valuable were those on selecting and purchasing angelfish (appropriate size and age, how to maximize chances of a breeding pair), genetic traits of fancy angelfish (veiltail, black, black lace, marble, new gold, commercial darks and marbles, non-allelic gold, smokey, chocolate, ghost, blushing, zebra, half-black, and pearly), breeding angelfish, and raising fry.
While I'm not interested in angelfish genetics per se, the descriptions of the fancy traits are very helpful when browsing the sites of angel breeders like Angels Plus. It also explains why some fish are so much more expensive than others.
History, tank selection (for show or breeding), feeding (the section on live food is better and more comprehensive than most I've seen in general aquarium books), diseases and treatment, and water quality are all well covered. The book has an index, glossary, and dozens of color photographs.