Well, the very old book Exotic Aquarium Fishes by Dr. William T. Innes was once the Bible of the aquarium hobby. Today it is still a must for every aquarists library as a history of this great hobby. It explains the basics of fish care that have not changed since Dr. Innes' day. Some information is very outdated however. It has a section on the most popular fish in the hobby and the basic needs of each. I think everyone should have a library of fish books. Today there is so much information on the internet that it is staggering. Books get out of date quickly sometimes but in most books there is all those little obscure bits of information that other sources gloss over. And then there is the old time joy of reading that the backlit screen can't duplicate. I like books.