Rach, J.J., S. M. Schleis, T. M. Schrier, and M.P. Gaikowski. 2002. Efficacy of 
chloramine-T to control mortality associated with external columnaris on walleye 
fingerlings (Stizostedion vitreum). Submitted to the U.S. Food and Drug Administration 
Center for Veterinary Medicine. January, 2003. 339 pp.
Summary
A clinical field trial was conducted at the Rathbun State Fish Hatchery (Moravia, Iowa) 
to evaluate the efficacy of chloramine-T to control mortality associated with external 
columnaris on walleye fingerlings. The treatment regimens were 0, 10 or 20 mg/L 
chloramine-T for 60 min (static) every-other-day for a total of three treatments. Each 
treatment regimen was tested in triplicate and each replicate contained 34 fish at test 
initiation. At the end of the trial, mean percent survival were 12.6% (control), 56.9% (10 
mg/L), and 34.3% (20 mg/L). The mean percent survival was significantly greater in fish 
treated with 10 and 20 mg/L chloramine-T compared to control fish that received no 
chemical treatment.