For the most part marine aquarists are interested in the wild coral reefs. These reefs offer a diversity of life that challenges, or perhaps exceeds, the rainforests.
Very many corals are now being propagated and fish, once thought impossible to breed are also being bred in increasing numbers of species. These actions are occurring with home aquarists and commercial organizations, a great benefit to aquarists and the wild reefs.
The problem that sometimes arises with reading material about the wild coral reefs that goes into any depth is that the material becomes entangled with science. Unless the reader is a scientist then interest is rapidly lost in the material. What is wanted is something beyond a hobby book that advises ‘how to’, though these are of course very important themselves (how many fish and corals are lost because the habitat when initially created was below standard?). The information should advise on what happens on a coral reef, habits and instincts, reproduction, in fact anything that is relevant to a layman, and all the better if the material permits the aquarist to choose the subject that is of interest and ignore any other.
There isn’t a requirement to be a scientist to achieve a successful reef or fish only aquarium, there is only a need to have a basic understanding of what is needed to properly support the life that is to be kept. Beyond this, each aquarist as an individual has more general interest or not.
Here’s a website that gives general information on wild coral reefs covering most of the areas that an aquarist could be interested in. It is written in a straightforward way and not bogged down scientifically, if I can put it that way.