Eel disease
The Aalrotseuche is a bacterial disease of river eels that live in fresh and salt water. It has been registered in Europe since 1928 . A distinction is made between the freshwater form, which is represented in European inland waters, warm water ponds and Japanese eel fattening systems , from the salt and brackish water forms that are common worldwide. It is named after the reddish discoloration of the fins, the abdomen and the anus region in the course of the disease.
trigger
Pathogens are bacteria such as pseudomonads or aeromonads (e.g. Aeromonas punctata ). These swim in the water and are normally harmless to healthy fish . They only become a danger when the water temperature rises above approx. 24 ° C, as the bacteria then multiply explosively and at the same time the oxygen concentration in the water drops, which causes stress in the fish. The oxygen content is particularly low on the ground and the concentration of bacteria is very high. This is an additional problem, as the eels stay there and even dig in during the day. When the temperature reaches 24 ° C, the protective function of the mucous layer on the skin of the eels is no longer given, so that the bacteria can penetrate.
Symptoms
Initial stage
The fish swim slowly and lazily. They also get red spots in the stomach and mouth area .
2nd stage
These affected areas of skin later grow together to form large areas (hence the name).
3rd stage
As the disease progresses , the skin becomes detached and large holes appear in the animal's body . These can also be bordered with ulcers .
Terminal stage
In the end, the eels swim to the surface in a noticeably curved shape and die.
treatment
No therapeutic methods are currently known and there is probably no research in this area. You can only remove the dead animals as quickly as possible. Although the dead eels do not pose a risk of infection for healthy eels and humans , they are still a source of infection .
hazards
It is safe for humans to eat fish that are not recognized but infected , as the bacteria die at temperatures above 60 ° C. Normally, only weakened animals are affected by the epidemic anyway.
In a regionally limited area, fish die off almost every year. In hot and long summers ( 1976 , 1991 and 2003 ), however, this is extremely strong.
