Control Techniques for Ichthyophthiriasis in Rainbow Trout Farming

 1. Symptoms Ichthyophthiriasis is also known as white spot disease. The parasite lodges on the body surface, oral cavity, eyeballs and gills of rainbow trout. Many white spots are visible to the naked eye at the parasitic sites. When the white spots are scraped off and placed on a drop of water on a slide, the white spots can be seen moving along the edge of the water drop. If it parasitizes the eyeballs, it can cause the eyeballs to become cloudy and white. When parasitizing the gills, it can increase gill mucus, cause the gill filaments to rot, and make the diseased fish have difficulty breathing.

2. Pathogen It is Ichthyophthirius multifiliis. 3. Epidemiology This disease mainly harms the juvenile stage of rainbow trout. It has a wide epidemic range and is a common and frequently occurring disease in rainbow trout farming. The onset water temperature is above 10°C, and the infection rate can reach more than 90%. It often causes acute death. 4. Control methods (1) Soak the diseased fish in a 5% salt solution for 1 minute or in a 1% concentration for 1 hour, with good results. (2) Soak in 1:4000 formalin for 1 hour.