What do you keep on you bookshelf that you consider to be indespensible for the fish you keep and what is it that you like most about it. For my GF I really like Fancy Goldfish by Johnson and Hess. The most useful book I have come across specifically for Goldfish. It is incredibly comprehensive, covering everything from setup up, to disease, treatment, breeding, and breeds. I really think the pictures are fantastic and useful in the case of diagnosing. And it is full of them.