Marine fish
With the advent of more efficient methods for keeping the water quality up, marine fish keeping in growing increasingly popular world wide. Marine species typically require very stable water values and really low levels of organic waste, since this is what they are used to from the wild. Even captive bred marine species tend to be more sensitive than your garden variety freshwater fish and are normally not recommended for novice aquarists. As you set up your first aquarium for marine fish, it is best to start with comparatively sturdy saltwater fish like damsels. It is however important to keep in mind that damsels can be quite aggressive, especially as they mature, and it might not be possible to safely add more docile species later on. As with freshwater aquariums, large tanks are normally easier to keep stable than small tanks since more space means that any pollutant or sudden increase in organic waste will be diluted by a larger amount of water. The added expense of getting a large aquarium instead of a small one is usually a good investment in the long run since sudden fish mass-deaths are less likely to occur. Marine fish tend to be quite costly, so planning ahead is crucial from a financial perspective.
