If you want to rely on books for actual, accurate info, then I think you're on a hide to nothing; research (even in fishkeeping, which is very poorly reasearched in general) moves very quickly and, bibliophile as I am; you'd be far better off looking on the internet and cross referencing.
On the other hand, if you're interested in ways of looking at fish and thinking about how to best house them, I'd recommend two books.
The first is Tropical fish; Freshwater and Marine Aquaria by Reginald Dutta. Technically it's hideously out of date, but his radical ideas on decor, and his sympathetic way of looking at the form and function of different fish to enable you to provide them with the best enviroment is, IMO, invaluable. Just don't believe him when he tells you oscars grow to 6"!
My second recommendation would be The Complete Aquarium by Peter Scott. Again, the technological advances make a lot of the hardware advice invalid (neither of those book mention fishless cycles, for instance), but as an inspiration on how to aquascape tanks for fish with specific needs it's mine of inspriration.
mainly as back up support sort of thing. Thanks for the advice on books 
