Velvet - Oodinium - Rust - Gold dust fish disease

Velvet - Oodinium - Rust - Gold dust fish disease

1. General description

The life cycle of parasite which is cause this disease we can divide into 3 stages. The first phase: the parasite attacks fins rays, gills, mucous membranes around the eyes, around nose, inside the mouth and skin. It penetrates in deeper epidermis layers with help its flagellates. Then it secretes enzymes which partly dissolve tissues and they are cause formation of small, whitish nodules. Next it leaves the host after accumulation of food stocks. It forms cysts and falls freely. The second phase: the parasite cell divides multiple inside the cyst. The third phase: these cysts crack after reaching maturity and new parasites in the zoospores forms look for a new host. Length of the whole life cycle depends on water temperature and illuminance (the parasite contains chlorophyll). The most optimal conditions for this parasite development is 23-25°C water temperature. Then zoospore needs to find a host within 24 hours because it will die after this time. It stays on the host for 3-4 days in this optimal water temperature.

2. Type of the disease

This is parasitic disease.

3. Cause of the disease

Causes of this disease are protozoa from Dinoflagellate group: Oodiniumpillularis and Oodiniumlimnetioum.

4. Favorable circumstances for development of the disease

• purchase of sick fish
• weakened immune system of fish
• too much fish in aquarium
• rapid changes of water temperature
• infected live or frozen food
• infected equipment, e.g. a net

5. Common symptoms of the disease

• excessive secretion of mucus
• single, small, white dots which look like powder, these dots form yellow-brown or gray, velvety coating with time
• loss of appetite
• rubbing
• clamped or frayed fins
• desquamation of the skin
• breathing problems – gills covered by mucus
• fast movements gill covers

6. Types of the treatment

This disease is often diagnosed in advanced stage. We may hasten biological life cycle of this parasite through increasing the water temperature and the light intensity. All drugs are effective only in the second phase of parasite life cycle – when it freely swims and looks for a new host. We may add salt into the water (1 table spoon per 5l) – then the fish will breathe easier. We need remove activate carbon from the filter before treatment. We cure the fish in a separate aquarium. We need increase the water temperature up to 25-28°C in the general tank on a few days. Then the parasites die without a host. All equipment (nets, buckets, substrate cleaners, hoses etc.) we need disinfect.

We may use one of the following medicines:

• copper sulphate: we add 0.2mg per every water litre, we do this bath for 10 days, we should repeat this dose after a few days if necessary,
• tetracycline:this is antibiotic, we dissolve 1 tablet in 50l of the water
• Odimor from Aquarium Münster company: we add 1ml per every 20l of the water
• trypaflavin from Zoolek company: long-term bath: 10ml per every 20l of the water, short-term bath: 10ml per every 5l of the water
• mycocid from Zoolek company: 1ml per every 20l of the water
• omnipur S from Sera company: 1ml per every 20l of the water

We need remove medicine from the water after conducted of the treatment – we use filter with activate carbon and we do gradual partial water changes.

7. Comments about this disease

• This disease is often confused with ich/white spot disease. The white dots make the basic difference because they are much smaller compared to ich dots. They are often visible at certain angle or in suitable lighting. Oodinum is also more destructive for the fish than white spot disease.
• This disease is very contagious.
• The life cycle of the parasite takes place the most quickly for optimal conditions (optimal water temperature and lighting). This cycle will be much slower in other conditions, e.g. darkening the aquarium won't kill the parasites.
• Young fish, fry, the Anabantoidei suborder, the Cyprinodontiformes order (especially from Valenciidae, Rivulidae, Aplocheilidae, Cyprinodontidae families), danio and gold fish are sensitive to this disease.

8. Prevention

• quarantine for new fish, plants, snails and other animals
• prophylactic baths for new fish
• disinfection of decorative elements
• properly number of fish, plants and other animals

9. Links with additional informations