Reference books for serious fish keepers, covering tetras and other characins (Tetraspedia 2), L-number plecos (Pleco Pocket Book), guppies (Guppypedia 1&2), Bornean hillstream loaches (The Borneo Suckers) and Horst Linke's books on Altum angelfish and Betta macrostoma.
Several of these titles are hard to find in local bookshops, and they are useful for identifying species, understanding their natural habitat and learning how experienced breeders keep them. They also make good gifts for fellow fish keepers. New titles are added from time to time, so check back.