Whats the difference between saltwater and freshwater?
Whereas freshwater fish are found in rivers, streams, ponds and lakes, saltwater fish are collected from oceans and seas. As such, their natural environment is quite stable and they do not readily adapt to major changes in water chemistry or temperature. In addition, since nearly all saltwater fish and invertebrates are captured in the wild (many freshwater fish are either tank or pond raised), there are greater risks associated with handling and shipping. The risks, shipping and collecting costs, and supply-and-demand also make saltwater specimens more expensive than their freshwater counterparts. What equipment is needed? Most modern aquarium equipment is designed to be functional in either salt or fresh water, but it is important to select quality, reliable supplies. It hardly pays to save six dollars on a heater or ten dollars on a filter system and risk the loss of twenty or thirty dollar fish. Contrary to some opinions, undergravel filters are not essential in saltwater aquariums
