If you plan on having fish you should have a number of tropical fish guides as reference material. No one is saying that you ought to read these each night but you have a duty to look after these lovely species. You can only achieve this if you have some idea of their habitats, appearance, health, habits etc.
There are many different kinds of fish it is almost impossible to be a specialist on all types. Having tropical fish guides to hand allows you to check if their behavior is normal or something that needs investigating. You may also check on what you need to be feeding the fish, in what amounts and over what time .
Books also can help give you guidance on the way to manage your aquarium. You must find out how and when to clean it out. You should also find out about managing a sick fish so that your entire fish tank doesn't become infected. If you are planning on breeding your existing fish you have to read up on this process before hand as it can cost considerable time and effort not forgetting money. Fish don't all breed in the same manner, some will release eggs that are fertilized outside the body. Others won't breed in captivity yet some will breed like bunnies. Reading won't teach you all you need to know but it will assist you to get onto the right path.
When you own a fish tank, you become 100% responsible for the needs of the species that live there. It is not sufficient just to keep water clean and give the fish food daily. It takes a lot more work than that. Reading various tropical fish guides will provide you with the knowledge to make your new interest far more enjoyable for you as well as the fish you own.