If you want a book about the requirements of different species of aquarium fish, the "bible" is perhaps Baensch's Aquarium Atlas vol. 1, which contains more species and more *reliable* information than anything else in its price bracket. I bought my copy in the late 80s and still use it regularly. I think it contains about 500 fish species and about 100 species of plant. Does have a few gaps, but nothing vol. 2, 3, etc. won't fill as you become more adventurous and experienced. It has good sections on filtration, lighting, etc. but these are a bit outdated in some ways and not particularly easy to read (translations from German to English rarely are).