How to treat koi with white spot disease? A full analysis of treatment methods
White spot disease is caused by the protozoan Ichthyophthirius multifiliis invading the skin or gills of fish. It is a relatively common disease in koi during spring and autumn. If not detected in time, the mortality rate is over 90%. Below we introduce how to treat white spot disease in koi from three aspects: symptoms, conditions under which it occurs, and treatment methods.
Symptoms of white spot disease in koi
Infected koi will be covered with white spots all over the body, and within the white spots the multiplying white spot larvae can be seen. They attach to the koi's body and multiply rapidly. The koi will rub against hard objects in the pond because of itching, gradually become thin, tend to float at the water surface, and move slowly. In the later stage of the disease, a white film appears on the koi's body, a lot of mucus is secreted, and the body surface becomes dull and lusterless.
Conditions under which white spot disease occurs in koi
The occurrence of white spot disease is clearly seasonal, generally occurring from December to June of the following year. When the water temperature is 14-25°C, it is the most suitable temperature for the reproduction of Ichthyophthirius multifiliis, and this is also the season when the disease is most common. When the water temperature is below 10°C or above 28°C, the development of Ichthyophthirius multifiliis larvae stops or they gradually die.
Treatment methods for white spot disease in koi
1. Ichthyophthirius multifiliis is not easy to reproduce when the water temperature is above 25°C, and begins to die at 28°C, so this can be used for prevention and control. After a few days, the cysts of Ichthyophthirius multifiliis will gradually rupture and fall off. At this time, replace with new water and keep the water temperature constant, and the sick fish will basically recover. If drug treatment is also used, the cure rate can reach over 90%.
2. Put a piece of furazolidone powder the size of a soybean into an aquarium containing 50 kg of water, dilute it, and splash it into the water for a medicated bath for the sick fish.
3. Soak a new brick in urine for 24 hours, take it out and let it dry (called a urine brick in ancient times), then put it into the tank with the sick fish, and results can be seen after a few days.
4. Choose 0.2-0.3 g of mercurous nitrate, dissolve it in 10 kg of water, and soak the sick fish for 10-15 minutes. Note that because mercurous nitrate is highly toxic and corrosive, the medicinal liquid should be placed in a plastic basin, not a metal container.
5. Use a 0.05%-0.07% concentration of mercurochrome solution in 10 kg of water, and soak the sick fish for 15-30 minutes, using the medication continuously for 2-3 times.
6. Treatment with red mercurochrome. The key to this method is not to add too much; it is enough for the water to be slightly red. Better less than more! Soak for 5-10 minutes, 1-2 times a day.
7. Add an appropriate amount of methylene blue medicine, 4-8 cc per 10 gallons of water. In a container without bottom sand and equipped with a filtration system, the dosage should be reduced to one-half to one-quarter.
8. Put the sick fish in 1% salt water and give a medicated bath for 3-5 days, and it can also be cured. Adult white spot disease parasites are difficult to kill, but the larvae are easy to kill, so maintaining an effective drug concentration in the water for about 7-20 days can completely wipe them out.