Gaikowski, M.P.,C. Densmore, J.J. Rach, W. H. Gingerich, and V. Blazer. 2000.  Toxicity 
Assessment of Hydrogen Peroxide To Cold-, Cool-, and Warmwater Fish.  Volumes I-III.  
Completion report for study CAP-97-00048-08.  Submitted to the Center of Veterinary 
Medicine, U. S. FDA.  October 2000.  177 pp.



Hatchery personnel depend on therapeutant treatments to control diseases.  Currently, 
hatchery managers in the United States are limited to one approved therapeutant 
(formalin) and three compounds of Low Regulatory Priority (sodium chloride, hydrogen 
peroxide, and acetic acid) to control external diseases of cultured fish.  Hydrogen 
peroxide has been used to effectively control external columnaris and bacterial gill 
disease in rainbow trout, however, data to document definitive safe treatment 
concentrations for hydrogen peroxide are lacking for a variety of species.  We report the 
acute toxicity and histopathology of hydrogen peroxide treatments to eleven species of 
fry (ten for histopathology) and thirteen species of fingerling freshwater fish.  Treatments 
described in this protocol are representative of a “worst-case” hatchery treatment regimen 
because the hydrogen peroxide treatment solution was allowed to gradually flush from 
the system.  Therefore fish were actually exposed to a gradually reduced hydrogen 
peroxide concentration for about 30 - 40 min after the treatment “termination”, ie. re-
initiation of fresh water flow.  Most mortality occurred within the first 30 h after the first 
exposure to hydrogen peroxide with little change in the overall shape of survival curves 
over time.  Our data predict that in an actual therapeutic application of hydrogen 
peroxide, most treatment-related mortalities would be observed shortly after the initial 
exposure.  Coolwater species were more sensitive than coldwater species but were 
generally similar to warmwater species tested.  Based on our mortality data, coldwater 
species and largemouth bass may be treated for <60 min at concentrations of <170 mg/L 
without harmful effects; all muskellunge, walleye, bluegill, channel catfish, yellow perch, 
pallid sturgeon fingerlings, fathead minnow fingerlings, white sucker fingerlings, and 
northern pike fry may be treated for <60 min at <100 mg/L; and northern pike fingerlings 
and white sucker, yellow perch and fathead minnow fry may be treated for <60 min at 
<60 mg/L.