Fish region
From an ecological point of view, fish regions are - essentially according to the occurrence of characteristic fish species ( key fish species ) - certain zones of flowing waters (streams and rivers from the source to the sea, lakes and canals through which they flow).
Standing water is divided into other ecological life zones: open water zone (pelagial) and bottom zone (benthal) .
Trout region
The trout region is usually located on the upper reaches of a river. There is a very strong current, which means that the water is circulated over gravel and larger stones and enriched with oxygen. The water temperature rarely rises above 10 ° C . The bottom consists of rock, rubble and coarse gravel.
- The main fish is: brown trout
- Associated with: bullhead , minnow and brook lamprey
Limnological classification: Epirhithral (upper trout region) and Metarhithral (lower trout region)
Grayling region
There is still a strong current and high oxygen level in the grayling region, but there are more plants than in the trout region. The water temperature here rises to 15 ° C, the subsoil consists of rubble and coarse to fine-grain gravel.
- The main fish is: grayling
- Associated with: nose , gudgeon , tailor , chub , burbot , sea trout , salmon and huchen (Danube region)
Limnological classification: Hyporhithral
- Trout and grayling regions are also collectively salmonids region (limnological Rhithral ), respectively.
Barbel region
In the barbel region the water temperature is around 15 ° C, the bottom consists of coarse-grained sand and fine-grained gravel . The flowing waters ( mirror widths ) are getting wider and the current is only weak. The oxygen content fluctuates and is lower than in the grayling region. The shore zone is rich in vegetation (with belts of reeds).
- The main fish is: barbel
- Associated with: Aland , asp , salmon and nerds (Danube region), hazel , Pickerel , roach , rudd and bream and catfish and sturgeon
Limnological classification: epipotamal
Bream region (lead region)
The bream region is the most species-rich fish region and is located on the lower reaches of a river. Temperatures are up to 20 ° C in summer, and the river often freezes over here in winter. The vegetation is very lush and the subsoil consists of fine sand, sometimes mud is deposited . The oxygen content is very low.
- The main fish is: bream (also called lead )
-
Associated with: bream , pikeperch , perch , rudd , roach , tench , eel and pike
- Wild carp , crucian carp , bleak , sturgeon and catfish can be found.
Limnological classification: metapotamal
- Bream and barbel regions are combined and also referred to as the cyprinid region (limnologically Potamal ).
Ruffe-flounder region
This region is already part of the brackish water area and is the last fish region. It is located in the delta of the mouth to the sea in the area of influence of ebb and flow . It is 20 ° C warm and warmer in summer. The subsoil consists of fine sand, gravel and mud. The oxygen content varies depending on the tides.
- The main fish is: ruff
-
Associated with: flounder , mullet , sturgeon and eel
- The three-spined stickleback and all fish in the bream region also occur.
Limnological classification: Hypopotamal
Classification of fish regions according to slope and width
According to DVWK (1996) and Huet (1949)
| Fish region / width of water | <1 m | 1-5 m | 5–25 m | 25-100 m | > 100 m |
|---|---|---|---|---|---|
| Gradient [‰] | Gradient [‰] | Gradient [‰] | Gradient [‰] | Gradient [‰] | |
| Upper trout region | 100-16.5 | 50-15.0 | |||
| Lower trout region | 15.0-7.5 | 14.5-6.0 | |||
| Grayling region | 6.0-2.0 | 4.5-1.25 | |||
| Barbel region | 1.25-0.33 | 0.75-0.25 | |||
| Bream region | 0.25-0 | ||||
| Ruffe-flounder region | 0 |