Effectiveness of Copper Sulfate and Potassium Permanganate on Channel Catfish Infected with Flavobacterium columnare

Abstract

Copper sulfate (CuSO₄) and potassium permanganate (KMnO₄) were evaluated for their effectiveness to curtail mortality and decrease bacterial load in fish tissues and water in channel catfish Ictalurus punctatus infected with Flavobacterium columnare, the causative agent of columnaris. Fish (average size, 16.6 g and 13.7 cm) were obtained from a single culture tank undergoing an epizootic of columnaris and were stocked at a density of 30 fish per tank in each of 12 tanks. The study consisted of three treatments (n = 4 replicates per treatment): an untreated control group, a CuSO₄-treated group, and a KMnO₄-treated group. Treatment rates were 2.1 mg/L CuSO₄ and 3.0 mg/L KMnO₄ and were applied on three consecutive days at 24-h intervals. Caudal fin, gill, and liver samples were taken from one fish of each replication 24 h after the last treatment for analysis by quantitative real time PCR. A significant improvement in survival was noted among fish treated with CuSO₄ (72.7%) compared with the control fish (38.5%) and the KMnO₄-treated fish (52.2%). Survival of the KMnO₄-treated fish was not significantly different from the control. Quantitative PCR indicated a significant reduction of bacteria in the water after the first and second treatments of both therapeutants; no difference was detected in fish tissues. Histological analysis of gill samples 24 h after the last treatment indicated that CuSO₄-treated fish exhibited significantly less gill damage than untreated controls and there was no difference in KMnO₄-treated fish. Copper sulfate therapy significantly improved survival, reduced the number of bacteria in the water, and reduced gill pathologies associated with F. columnare infection in channel catfish.

Received August 23, 2011; accepted November 22, 2011

ACKNOWLEDGMENTS

The authors thank Matt Barnett and Cindy Ledbetter for their technical assistance throughout the course of the study. We are grateful to Matt Griffin, Steven Rawles, and Ben LaFrentz for constructive comments and review of early manuscripts. This study was funded by the U.S. Department of Agriculture (USDA), Agricultural Research Service under Project 6225–32000–004–00D. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. The USDA is an equal opportunity provider and employer