Fish are much more susceptible to disease than they are stressed. The most important are infectious diseases including parasitoses, water-related damage and stress factors in the housing conditions. Injuries, hereditary diseases, malformations and tumors also occur in fish.
Some infectious diseases can lead to mass loss in fish farming. They are then referred to as fish diseases and are subject to legal measures in accordance with the Animal Health Act, special legal regulations or EU legal provisions.
In Germany, four fish diseases are currently classified as notifiable animal diseases: contagious anemia of the salmon, infectious haematopoietic necrosis and viral hemorrhagic septicemia of the trout as well as the koi herpes virus infection of the carp. The infectious pancreatic necrosis of the salmonids (IPN) is subject to notification.
There is a complex interdependency between the defense capabilities, the pathogens and the living conditions, which ultimately decides on the outbreak of infectious diseases. Different factors can trigger stress. This includes everything that makes fish restless and disturbs their rhythm of life, such as constant handling in the water, but also constant changing of the light-dark phases. Worsened water parameters, such as a lack or excess supply of oxygen, excessive ammonium, nitrite or CO content, are also considered a stress factor2nd, as well as unfavorable pH values, incorrect water temperature, lack of hiding places, wrong choice of species, or excessive flow.
Stress weakens the animal's ability to defend itself. As a result, they cannot maintain an immune imbalance with the most ubiquitous pathogens. Only then does an infection become a breaking „disease“.
Stress triggers:
- High ammonia values
- Increased nitrate levels
- Wrong pH of the water
- Fluctuating temperature
- Unsuitable salinity
- Low oxygen content
- Harassment by other fish
- Inadequate pool size
- Too many fish in the pool
- Excessive use of medication
- Poor diet
- Sudden changes in water chemistry
- Improper use of water treatment agents
Stress indicators:
- Loss of appetite
- Increased gill movements
Diseases and unicellular parasites can cause a variety of symptoms in infected fish:
- Some fish have difficulty swimming and lose their balance and buoyancy.
- Sick fish often hold their fins flat against the body.
- You may see your fish lying on the side of the tank or pond floor.
- Some conditions can lead to higher mucus production, which leads to cloudy spots on the flanks of the fish.
- Another symptom is an inflated stomach of the fish. Outstanding or damaged scales.
- A fish with a weakened immune system is more likely to develop a fungal infection that can form gray growths that look like cotton on the scales.
- Harmful bacteria can cause the gills to look red and irritated. The gills may remain open when the fish has gill mites.
Fin rot and bacterial infections can cause the tail and fins of a fish to look frayed.
Stressed fish cannot defend themselves against parasites such as anchor worms or lice.
Aquatic addiction, which occurs in fish with a fluid accumulation under the scales, can also indicate the presence of bacteria.
Stress-related illnesses:
Because the causative agent of ichthyophthiriosis is a weak parasite and the puncture disease actually breaks out mainly when the fish is stressed, the stress for the animals in the aquarium should be reduced as much as possible. This includes stocking density, temperature, lighting, etc.
This article includes. Excerpts from the Wikipedi contribution fish disease: https://de.wikipedia.org/wiki/Fischkrankheit
Context:
ID: 406
