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 µL/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 µL/L), 
7% (100 µL/L), and 37% (200 µL/L); chinook salmon (Trial 2) 21% (control) 
7.6% (50 µL/L), 22% (100 µL/L), and 72% (200 µL/L); and rainbow trout 
(Trial 3) 31% (control), 25% (50 µL/L), 14% (100 µL/L), and 7% (200 µL/L).  
Exposures of 200 µL/L for 60 min increased the risk of mortality to brown 
trout and chinook salmon relative to other treatment concentrations.  
Exposures up to 200 µL/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 µL/L (Trial 1) as a 60 min exposure or hydrogen 
peroxide administered at 50, 100, or 200 µL/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.