# Marine Aquaria/Introduction
## For the new Marine Aquarist

So you are thinking about the hobby of marine aquaria? Obviously "marine aquaria" is somewhat ambiguous considering that there are many configurations that may still fall under the category of reef tanks. From the miniature "Nano" set-ups to massive systems in excess of one-thousand gallons, there are as many variations in the hardware and technique as there are in types and configurations of the livestock that are kept.
That being said, it should be a primary concern of yours to determine up front what your intentions are in the mid to long term with your aquarium. Unless you have a surplus of time or money, deciding up front and planning how to build your aquarium can make the difference between success and failure and, by extension, satisfaction or frustration. Simple decisions like whether to choose a particular type of protein skimmer or test kit can make massive differences over time in your enjoyment of the hobby.
It is important to study up so you can make knowledgeable decisions. Many mistakes can be made simply by not knowing any better. By doing a little research into the hobby you can avert disaster. This book gives an introduction to the marine hobby.

## Types of Marine Aquaria

Strictly speaking, a marine aquarium is purely defined by the amount of salt in the water. If your aquarium has water as salty as the ocean, it can be considered marine. There is no other prerequisite for the aquarium to be considered marine. You can have fish from a single region of the sea or you can have fish from all over the world. It makes no difference. Obviously, the term marine in the aquarium hobby is still quite a broad term. There are a number of configurations of marine aquariums, including Fish Only, Fish Only With Live Rock, Reef, and Nano.
Fish Only, shortened FO, refers to keeping an aquarium with only fish. Perhaps there may be some sort of decoration, but you are only keeping fish. FO is often the set-up for fish that will eat invertebrates, damage coral, or do not live in reef habitats. This set-up is by far the cheapest way to go.
Fish Only With Live Rock, shortened FOWLR, is a set-up where fish are kept with what is known as Live Rock. Live Rock will be discussed in further detail later, but it is basically rock with living organisms on it. Because of this, technically you are not keeping Fish by themselves. In a FOWLR aquarium, the aquarist may also add some other invertebrates. However, Live Rock has a price tag, and so FOWLR is generally more expensive.
A Reef refers to housing coral. This may or may not include fish. Keeping a reef is by far the most expensive configuration of marine aquaria. Many extra costs go into housing corals besides the corals themselves. On the other hand, housing a reef can be extremely rewarding as it is an extremely beautiful way in which we can mimic nature on our own homes.
The Nano configuration only refers to the size of the aquarium and nothing more; a Nano can be an FO, an FOWLR, or a Reef. There is no solid distinction, but a Nano aquarium is a relatively small aquarium. Because of their small size, Nano aquariums are more difficult to maintain and are virtually an experts-only area.
Still, there are other categories.
A species aquarium refers to having only one species in the aquarium. This may be optimal in many cases, either if the species of interest is extremely delicate or requires very specific parameters, which is the case for housing most seahorses. On the other hand, a species tank may be the set-up if the species poses a danger to most other organisms that would be placed with it, such as sharks.
A community aquarium refers to having a range of species in an aquarium, and is much more common than a species aquarium. It adds another layer of difficulty in having to figure out what organisms are compatible with each other, but it can also be more rewarding.