The fish lives in the water. Once the water is different in composition: fresh, sea, brackish sea. And the fish are conventionally divided “place of residence”.
Live in marine salt water. There are approximately 000 species of 11.6. They are divided into living in the water column (pelagic) – anchovies, mackerel, Bonito; living in the surface layers of the ocean – tuna, flying fish; bottom – stingrays, flounder, sculpin. There are also fish that live in coastal waters.
They live in fresh water: rivers, lakes, ponds. There are about 8 000 species.
The so-called fish for life change dwelling place, move from seawater to freshwater for spawning (herring, sturgeon, salmon) or from fresh water floating in salt water in order to lay eggs, such as acne.
These fish are found in brackish marine areas. These fishes are gobies, flounders, pipefish.
The common sturgeon in rivers of the Black, Caspian, White and Kara seas
Let us consider the main types of fish ecosystems: rivers, lakes, seas.
There are lakes with different nutrient content. The lake is called oligotrophic, few nutrients, usually it is a deep lake. Atrisinasanas a small lake where a lot of nutrients. To determine how many fish in the lake, analyzing its swimming pool is the gathering place of precipitation and climate. If a lake receives nutrients from municipal sewage, then this factor will contribute to the growth of eutrophic species (many cyprinids), but will be detrimental to salmon. The main source of food for young fish, and some species of adult fish is plankton. The movement of phytoplankton depends on water flow. Makes daily zooplankton migration in the surface water goes out at night, to a depth returns in the afternoon. Consequently, changing the movement of the fish. Near the shore are usually the most species of life, the deeper – the poorer habitat. Depending on changes in temperature, changes its habitat for pike, she’s looking for cold water, so in spring and autumn pike will dwell in shallow waters, and in the summer will seek cooler temperatures in the depths of the lake. Perch, for example, more heat-loving fish. Responds to minor changes in temperature, looking for a place warmer. The coastal area is tied trout.
Streams, rivers, and the rivers are all flowing water bodies. Rainbow trout is a freshwater form of Steelhead salmon. Holodova fish
In the river where the current is fast, cold, oxygen saturated water, which flows on the rocky bottom. Plankton in such conditions is delayed badly, fast ducts the water to grow algae, mosses, lichens on stones. The fish living in the rapid current of the river is more streamlined, oblong body shape. For example, salmon and trout live in the rapid river.
When the current is weaker – the water is saturated with enough oxygen, depth more. The bottom is covered with sand and gravel. Such areas are, for example, goby, and catfish.
The slow flow of the river water is saturated with oxygen moderately, the temperature is higher at the bottom of the gravel. Such conditions are suitable for eel and perch.
Pike lives in areas with moderate and weak currents
When the river resembles a pond – the water is turbid, the bottom silt. A great variety of river plants. A lot of nutrients. Such habitat from carp, pike.
Experienced anglers know that there are places of a congestion of fishes at the outlet of the lake. This is because in such places accumulate small organisms, filter feeders, they try to resist, to capture a mixture of plankton, insect larvae, dead organic material that carries current. These interesting fish species of large fish, which itself behaves as a filtration organism, selecting a favorable place, and seizing everything that floats past. So behave in the water stream, young salmon, grayling, rainbow and brown trout.
Plaice lives on the seabed
Due to the vast area of ocean, when its great depth (an average of 3,800 meters), marine organisms more space for living. Also in the sea is phytoplankton (algae, flagellates) and zooplankton (crustaceans, krill). Large fish food are molluscs, small fish and birds.
The water temperature varies depending on the distance from shore and depth. The closer to the shore and to the surface of the water – the warmer, but the sea fauna is poorer in its variety. Fish living in sea water, is well adapted to the conditions, are found at all depths. An example of adaptation to environmental conditions can be flounder, with its flat body, tuna, whose body resembles a torpedo, he can swim very fast and live at great depths. But more species of fish, of course, in coastal areas, where more sites covered with algae, mud banks, and therefore, more nutrients. Basically, the choice of habitat in the sea is dependent on water salinity, flow velocity, depth.