Ichthyosporidium fish disease

Ichthyosporidium fish disease

1. General description

This is one of the most dangerous fish diseases. When fish have advanced symptoms then effective treatment is impossible. Both freshwater and saltwater fish suffer on this disease. Its symptoms are difficult to diagnose because they are similar to other diseases. Cause of this illness is kind of fungus (recently classified as a protozoan) which life cycle we can divide into a few stages. Spores of this fungus (spherical cysts) get to fish organism mostly through its digestive system. These spores release ameobids (unicellular forms) which penetrate the mucous membrane of intestines and they migrate anywhere with the blood. Then these protozoans multiply, divide and form new spores in a particular organ. The new spores get back into the water (they are excreted through the skin – gills, injuries and digestive system – the excrement) and they are waiting for a new host. The new spores are formed in the host body after 10 days and they can survive without a host or in unfavorable environment up to 6 months. This protozoan attacks internal organs most of all: the liver, kidneys, heart, brain and muscles. The disease progresses sharply or chronically. The life cycle of this fungus much accelerates and it lasts shorter in higher water temperature.

2. Type of the disease

This is fungal disease.

3. Cause of the disease

Cause of this disease is fungus Ichthyophonus hoferi.

4. Favorable circumstances for development of the disease

• weakened immune system,
• bad water conditions,
• infected food (marine fish, invertebrates),
• too much fish in aquarium,
• mechanical injuries,
• insertion a new infected fish.

5. Common symptoms of the disease

• movement disorder and imbalance, characteristic abrupt movements, rocking from side to side, loss of body colours (effect of nervous system infection),
• body cavity exudation, dropsy, protruding scales, weight loss, white nodules in the internal organs (effect of infections of liver, kidneys, spleen, etc.),
• small, tactile hand nodules on the skin, sores and skin defects (effect of muscles infections),
• breathing problems, swimming under water surface, necrosis of gills (effect of gills infections),
• bulging eyes (effect of eye infection),
• loss of appetite,
• apathy,
• hiding.

6. Types of the treatment

This is incurable disease. The treatment isn't effective – the cyst walls are resistant to antibiotics. When we suspect this disease we should separate potentially healthy and sick fish. The healthy fish we observe or we may do a disinfectant bath for them. The sick fish with advanced symptoms we should immediately commit an act of euthanasia. The general tank, substrate, decorative elements we must disinfect.

7. Comments about this disease

• Symptoms of this disease are similar to other illness as fish dropsy disease or fish tuberculosis.
• Sick fish often suffer secondary bacterial or fungal infections..

8. Prevention

• we always quarantine new fish for minimum 2-4 weeks,
• we may do a prophylactic, 30-minute bath for new fish in a solution of methylene blue or potassium permanganate,
• we use only food from a reliable source,
• we should disinfect the food or we should freeze it (below -10°C)
• we may use UV light for water sterilization,
• we should keep properly water parameters in aquarium,
• we never keep too much fish in single aquarium,
• we appropriate care of hygiene tank.