A. Cause: Piscinoodinium sp. (syn: Oodinium sp.)

B. Characteristics of pathogens:

     Is a round-shaped ecto-parasite.

- In the parasitic phase, it is shaped like a pear, surrounded by a membrane and a zoid-like appendix which is used as a tool to attach to fish. The duration of this phase depends on the temperature of the water, at a temperature of 25 o C for ± 6 days it will reach adult size.

- Severe infections for this disease can kill fish up to 100% within a few days.

- Fish organs that are targeted for infection include the skin, fins and gills of fish.

   - After reaching adult size, this parasite will break away from the host, and will turn into tomont and divide into a gymnospore. Gymnospore is an infective stadium that swims like a spiral to find a host, if within 15-24 hours Gymnospore does not find a host, the stage will die.

C. Clinical Symptoms:

- The fish will look restless, the gill cover on the fish will expand, the fins fold, and the fish will be thinner. Parasitic populations on the skin Result in rusty or brownish (decay) white color so it is often called "velvet disease".

- Fish usually do sudden movements, fast and unbalanced "flashing" and will be seen clearly in the morning or evening.

- Fish will rub the body hardened around it, and the body color becomes pale.

D. Diagnosis:

- Visual observation of the presence of parasites on the skin, fins and gills of fish.

E. Control:

- Maintain the pool water temperature so that it is always> 29 0 C

- Transfer of fish populations infected by parasites to water that is free of parasites 2-3 times at 2-3 day intervals.

- Treatment and / or eradication of parasites in fish, among others, can be done through immersion by:

    1. Salt water (1-10 gr / liter, depending on species and size of fish) for several hours, is transferred to parasite-free water and repeated every 2-3 days.

        2. Solution of hydrogen peroxide (H2O2)

at a dose of 150 mg / liter for 30 minutes, the fish is transferred to water that is parasite free and repeated every 2 days.

  3. cupric sulfate solution (CuSO4) at a dose of 0.5-1.0 mg / liter for 5-7 days with strong aeration, and water must be replaced every day.