Aquarium

Marine aquarium
A marine aquarium is an aquarium that keeps marine plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only (FO), fish only with live rock (FOWLR), and reef aquaria. Marine fishkeeping is different from its freshwater counterpart because of the fundamental differences in the constitution of saltwater and the resulting differences in the adaptation of its inhabitants. A stable marine aquarium requires more equipment than freshwater systems, and generally requires more stringent water quality monitoring. The inhabitants of a marine aquarium are often difficult to acquire and are usually more expensive than freshwater aquarium inhabitants. However, the inhabitants of saltwater aquariums are usually much more spectacular than freshwater aquarium fish.

Types of marine aquarium

Marine aquarists typically divide saltwater aquariums into those housing fish only, fish with live rock and those primarily designed to house corals and other invertebrates (also known as reef aquariums).

Live rock
Live rock is rock that has been in the ocean, composed of limestone and decomposing coral skeleton, usually around a coral reef such as those around Fiji, and is usually covered with beneficial algae, coralline and tiny invertebrates and bacteria that are desirable in the aquarium. Some examples of the microfauna commonly found on live rock are crabs, snails, feather dusters, brittle stars, starfish, limpets, abalones, and an occasional sea urchin, sea anemone, coral, and sea sponge. Also, if the aquarist is unlucky, a mantis shrimp. Bristleworms are also common, most of which, while unattractive, are not harmful and are useful scavengers; some species can be pests, however. The addition of live rock is one of the best ways to ensure a healthy aquarium, as the rock provides a buffer to maintain high pH (8.0-8.3), alkalinity, and acid-neutralizing capacity. Alkalinity is often known by a rather confusing term, "carbonate hardness", or KH. This is usually measured in "degrees" (dKH) or meq/L.

The microfauna found on live rock are detrivores and herbivores (as they eat algae and fish waste), and provide fish with a natural, attractive shelter. Live rock usually arrives from online dealers as "uncured", and must be quarantined in a separate tank while undergoing the curing process, which involves the inevitable die-off of some of the rock's inhabitants and the subsequent production of undesirable ammonia and nitrite. Live rock that is already cured is available at most pet stores that cater to saltwater. Live sand is similar to live rock and is equally desirable.

Reef aquarium
A reef aquarium or reef tank is an aquarium containing live corals and other animals associated with coral reefs.

These aquarium setups vary from having many fish that vary from chlorinating fish and spawning fish, which attempt to recreate life specific to one region of the world like the Great Barrier Reef, to the more prevalent and often spectacularly colored mixed reef that blend hard and soft corals from around the world.

Unlike the marine aquarium, which are built to house various types of fish, the main attraction in many reef tanks are the varieties coral and other invertebrates.