By: Kelsey Outram
Brackish water has more salinity than freshwater. Brackish water condition commonly occurs when fresh water meets seawater. In fact, the most extensive brackish water habitats worldwide are estuaries, where a river meets the sea. River estuaries form important staging points during the migration of some fish species, such as salmon, shad, and eels, giving them time to form social groups and to adjust to the changes in salinity. Estuaries are also commonly used as fishing grounds, and as places for fish farming or ranching. Another important brackish water habitat is the mangrove swamp. Like estuaries, mangrove swamps are extremely important breeding grounds for many fish, with species such as snappers, halfbeaks, and tarpon spawning or maturing among them
Fresh Water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The source of almost all fresh water is precipitation from the atmosphere, in the form of mist, rain and snow. Many species of fish do reproduce in freshwater, but spend most of their adult lives in the sea. These are known as anadromous fish, and include, for instance, salmon and trout. Some other kinds of fish are, on the contrary, born in salt water, but live most of or parts of their adult lives in fresh water; for instance the eels. These are known as catadromous fish.
Salt water is waterfrom a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5%. Seawater contains more dissolved ions than all types of freshwater. However, the ratios of solutes differ dramatically. For instance, although seawater contains about 2.8 times more bicarbonate than river water based on molarity, the percentage of bicarbonate in seawater as a ratio of all dissolved ions is far lower than in river water. Salt water contains many species of fish and sea life. Coastal Fish inhabit the sea between the shoreline and the edge of the continental shelf. Coastal fish include forage fish and the predator fish that feed on them. Deep sea fish are fish that live in the darkness below the sunlit surface waters. The lanternfish is, by far, the most common deep-sea fish. Pelagic fish live in the pelagic zone of ocean or lake waters - being neither close to the bottom nor near the shore. The marine pelagic environment is the largest aquatic habitat on Earth, occupying 330 million cubic miles, and is the habitat for 11 percent of known fish species.