Treatment of Ciliated Protozoan Infections in Fishes

July 16, 2024 Agric4Profits

Ciliated protozoan infections in fishes are illnesses caused by tiny, single-celled organisms called protozoa that have small hair-like structures called cilia. These cilia help the protozoa move and attach to the fish.

When fish get infected, the protozoa can cause problems like irritation, difficulty breathing, and damage to the skin and gills. This can make the fish sick and can spread easily in crowded or dirty water. Treatments often involve improving water quality and using medications to kill the protozoa.

Several chemicals commonly used to control ciliated protozoan in freshwater fish are listed below for your convenience. As stated above, the most ciliate infestations respond to one chemical treatment; however, fish that do not improve as expected should be rechecked and retreated if necessary. Overtreatment with chemicals can cause serious damage to fish.

Treatment of Ciliated Protozoan Infections in Fishes

Copper sulfate is an excellent compound for use in ponds to control external parasites and algae; however, it is extremely toxic to fish. Its killing action is directly proportional to the concentration of copper ions (Cu ⁺⁺⁾ in the water.

As the alkalinity of the water increases, the concentration of copper ions in the solution decreases. Consequently, a therapeutic level of copper in water of high alkalinity would be lethal to fish in the water of low alkalinity.

Conversely, a therapeutic concentration of copper in water of low alkalinity would be insufficient to have the desired action in the water of higher alkalinity. For this reason, the alkalinity of the water to be treated must be known in order to determine the amount of copper sulfate needed.

The amount of copper sulfate needed in mg/L is the total alkalinity (in mg/L) divided by 100. For example, if the total alkalinity in a pond is 100 mg/L, the concentration of copper sulfate needed would be 100/100 or 1 mg/L.

If you are unsure how to measure the alkalinity of your water, or have never used copper sulfate, contact your aquaculture Extension specialist for assistance. Never use copper sulfate in water that has total alkalinity less than 50 mg/L.

Due to its algicidal activity, copper sulfate can cause dangerous oxygen depletions, particularly in warm weather. Emergency aeration should always be available when copper sulfate is applied to your system or ponds.

Copper sulfate should not be run through the bio-filter on a recirculation system as it will kill the nitrifying bacteria. If possible, tanks should be taken offline during treatment with copper sulfate.

If necessary, clean the bio-filter manually to decrease organic debris and residual parasite load. Potassium permanganate is effective against ciliates as well as fungus and external columnaris bacteria, and it can be used in a pond or vat. Multiple treatments with potassium permanganate are not recommended as it can burn gills.

Aeration should be available when potassium permanganate is used because it is an algicide and can cause oxygen depletion. Potassium permanganate at the prescribed dosage (2 mg/L) does not seem to affect the nitrifying bacteria in a biological filter; however, ammonia, nitrite, and pH should be closely monitored following treatment.

Formalin is an excellent parasiticide for use in small volumes of water such as vats or aquaria. It is not recommended for pond use because it is a strong algicide and chemically removes oxygen from the water.

Vigorous aeration should always be provided when formalin is used. Used in proper amounts, salt effectively controls protozoans on the gills, skin, and fins of fish. This is an effective treatment for small volumes of water such as aquaria or tanks.

Use in ponds as a treatment is generally not recommended due to a large amount of salt and high cost of treatment that would be needed to be effective. Salt should never be used on fish that navigate by electrical fields such as knife fish and elephant nose fish.

When using any treatment for fish, a bioassay (a test to determine safe concentration) should be conducted on a few fish before large numbers of fish are exposed.

Fish species can react differently to various concentrations of the chemical; therefore, fish undergoing treatment must be monitored closely for adverse reactions. If the fish negatively react to treatment, the chemical should be flushed immediately from the system, or the fish should be moved to fresh water.

In summary, the parasite commonly causes disease in fish. There are various types that can easily be identified with a light microscope and can be treated with chemicals such as parasiticide and algicide. Chemicals should be handled carefully not to contaminate the environment.