Marine aquarium is also called as salt water aquarium. Fishes that are able to live in salt water are put up in a marine aquarium. To set up a Marine aquarium salt particularly formulated for a salt water aquarium must be adding to the water. To maintain the hardness and calcium at high levels, crushed coral and aragonite are be used in a marine aquarium. Marine aquarium can be decorated with corals, coral skeletons, sea shells, and any other calcium containing things. Make sure the aquarium is not over crowded the numbers of fishes that can be kept unharmed in a marine aquarium are one fish for 7 gallons of water or if the fishes are small in size that is one inch or lesser you can keep 1 fish for every 5 gallons of water. For beginners of salt water aquarium owners it is best to opt for a big tank rather than a small one because the harness and water quality is easy to maintain in big tanks than small ones.