The Baensch Aquaium Atlas series, lots of fish, lots of information, unfortunantly, it was translated from German to english so there are a few errors in it here and there, but they arn't too much of a problem
I like the internet the best and this forum is really invaluable (crawl, crawl - no honestly!) But I have a book that I am definitely fond of - "Tropical Fishlopaedia: A complete guide to fish care" by Mary Bailey and Peter Burgess. No pretty pictures but absolutely stuffed full of useful information. Bought is as a complete novice and it was just fab for learning about stuff from scratch.
I had a book somwhere called "fish health" or somthing which is a bit old but still good and it teaches you on how to do fish post mortem examinations and how fish meds work and it also lists alot of the realy rare deseases/parasites which is useful.
at work we also have one of those "encylopedia" type books and it covers a great range of fish with often correct information. only spotted a couple dodgy sizes so far, its by Gina Sandford i think it is.
I have quite a few books, but most are pretty much the same thing.
But 2 are good for novices and developed aquarists.
Freshwater Aquariums for Dummies and The Simple Guide to Freshwater Aquariums.
Also a subscription to Tropical Fish Hobbyist and Aquarium Fish magazine are super for learning about new things and learning more about others.
The magazines i consider should be a definite buy.
They both have websites using their names and you can purchase them there.
I use 3 on a regular basis, as well as the net, and this forum. I got 2 as gifts for christmas the year I started fishkeeping. They are fabu books, and all the info from them has been correct. I often pull them out when someone here is asking about a fish and isn't getting a lot of responces.
and I cant find the third one, but it's all about plants and that kinda thing.