Rach, J.J.,  M. P. Gaikowski, and R.T. Ramsay.  2000.  Pivotal Dose Titration Studies to 
Evaluate the Efficacy of Hydrogen Peroxide to Control Mortalities Associated with 
External Flavobacter Infections on Cultured Fish and Selected Fish Hatcheries.  
Submitted to the U.S. Food and Drug Administration Center for Veterinary Medicine.  
February 4, 2000.   339 pp.

The efficacy of hydrogen peroxide to control mortalities associated with bacterial gill 
disease was evaluated in three clinical field trials conducted at two Wisconsin 
Department of Natural Resources hatcheries.  Microscopic examination of the fish gills 
before treatment revealed gill damage and the presence of bacteria indicative of BGD.  In 
separate trials, brown trout (Salmo trutta; trial 1), chinook salmon (Oncorhynchus 
tschawytscha; trial 2), and rainbow trout (Oncorhynchus mykiss; trial 3) were transferred 
from the source culture unit into a test system of 12 individually plumbed tanks.  Each 
tank was supplied with a continuous flow of hatchery water at a flow rate providing an 
exchange rate proportional to that of the culture unit.  Fish were exposed to hydrogen 
peroxide concentrations of 0, 50, 100, or 200 無/L for 60 min 
(trials 1 and 2; Wild Rose Hatchery) or 30 min (trial 3; Osceola Hatchery).  In each trial, 
one treatment was administered  every-other-day on three occasions.  In all three trials, at 
least one of the hydrogen peroxide treatment regimens reduced cumulative fish mortality 
in comparison with the controls.  The percent mortalities for individual species tested in 
separate trials were as follows: brown trout (Trial 1) 12% (control), 0% (50 無/L), 7% 
(100 無/L), and 37% (200 無/L); chinook salmon (Trial 2) 21% (control) 7.6% (50 
無/L), 22% (100 無/L), and 72% (200 無/L); and rainbow trout (Trial 3) 31% (control), 
25% (50 無/L), 14% (100 無/L), and 7% (200 無/L).  Exposures of 200 無/L for 60 min 
increased the risk of mortality to brown trout and chinook salmon relative to other 
treatment concentrations.  Exposures up to 200 無/L hydrogen peroxide for 30 min 
decreased the risk of mortality to rainbow trout.  Post-treatment qualitative gill 
examinations indicated that gills of treated fish appeared normal (no signs of gill damage) 
whereas the gills of control fish were pale and had clubbed filaments, and lamellar fusion.  
Based on the efficacy data, five static bath treatment regimens were effective in the 
control of BGD;  hydrogen peroxide administered at 50 (Trial 1 & 2) or 100 無/L (Trial 
1) as a 60 min exposure or hydrogen peroxide administered at 50, 100, or 200 無/L as a 
30 min exposure.  Prior to administering any proposed treatment regimen, a preliminary 
bioassay should be conducted on a small sample of fish to verify the safety of the 
treatment.