Before you buy your marine fish tanks, be sure you know what kind of fish you want to have. There are both tropical marine fish and coldwater marine fish. You can not mix and match fish from these different groups – they need a strict water temperature maintained (tropical fish require warm water, and coldwater fish, quite obviously, require cold water). The fish are used to being out in open water where the temperature does not change often – therefore, you must keep the temperature of your tank fairly constant.
Know that water chemistry can be hard to maintain. Saltwater marine fish tanks are not necessarily the best tanks for beginners. It may be best to start with a freshwater tank before moving onto the task of keeping salt levels and other levels right in a saltwater aquarium. To keep the right salinity, evaporated water must regularly be replaced.
It is generally believed that marine fish tanks should not be left attended for more than just 2 days. They require constant maintenance (but only a little at a time…). Be aware of the care and maintenance required before you invest in any type of aquarium.