Efficacy of Potassium Permanganate in Treating Ichthyophthiriasis in Channel Catfish

Epizootics of ichthyophthiriasis can be controlled with potassium permanganate (KMnO4), but its effectiveness has not been confirmed by controlled studies. The purpose of this study was to determine the concentration of KMnO4 needed to halt an active Ichthyophthirius multifiliis infestation in channel catfish Ictalurus punctatus. Juvenile channel catfish were exposed to fish infested with I. multifiliis until they developed immature trophonts. They were then moved to individual static containers with 2 L of filtered well water, where they were treated with KMnO4 daily for 10 d. The lowest effective dose of KMnO4 required to eliminate theronts was 1.25 mg/L. The results indicate that KMnO4 is effective for controlling I. multifiliis epizootics at low concentrations in clean water. However, effective treatment in ponds will be strongly influenced by detoxication of KMnO4 depending on the concentration of easily oxidizable substances in the water.