Gaikowski, M.P., J.J. Rach, W.H. Gingerich, and G.R. Stehly.  1998.  Hydrogen 
peroxide treatment toxicity to rainbow trout eggs.  Part 2: Identification of sensitive 
periods during incubation of rainbow trout eggs..  Final report submitted to Division of 
Therapeutic Drugs for Food Animals, Center for Veterinary Medicine (FDA).  April 24, 
1998.  228 pp.

The data collected for this report was initially collected as described by the protocol 
“Toxicity of hydrogen peroxide to salmonid eggs and fry”, study number TOX-94-
00048-4.  After initial data collection, it became apparent to the study director that 
changes were required to collect data that would more accurately describe the toxicity of 
numerous antifungus agents, therefore, the protocol “Toxicity of hydrogen peroxide to 
eggs and fry of cold-, cool-, and warmwater fish species”, study number CAP-96-00048-
2, was drafted.  A memo (Appendix 1) was submitted by the study director to the Quality 
Assurance Officer at the Upper Mississippi Science Center on 06 February, 1997, 
combining the data from both studies under one encompassing study number, CAP-96-
00048-2.  Three lots of rainbow trout (Oncorhynchus mykiss) eggs were incubated and 
exposed to fifteen minute hydrogen peroxide treatments (0, 500, 1000, and 3000 ?L/L) 
administered every weekday (Monday-Friday) to determine embryo sensitivity to 
hydrogen peroxide treatment.  The treatment concentrations used were multiples of the 
Low Regulatory Priority limit of 500 ?L/L.   Embryo sensitivity was assessed by 
monitoring daily mortality and determining the time interval that the hydrogen peroxide 
treatment is most toxic.  Control and treated eggs from all lots tested remained free of 
fungal infection throughout incubation.  During testing of embryo sensitivity, daily 
percent mortality of rainbow trout eggs increased significantly between days 6 and 10 (78 
to 135 Daily Temperature Units ?C) of incubation.  The mean percent hatch of rainbow 
trout eggs treated with hydrogen peroxide at concentrations up to 1000 ?L/L may be 
increased if no treatments are administered between 70 to 140 DTU ?C.  Mortality of sac-
fry was not observed at hydrogen peroxide concentrations <1000 ?L/L.  Fish culturists 
should be aware that other species or strains may be more sensitive than rainbow trout.  
Other species and strains should be initially treated with hydrogen peroxide at 500 ?L/L 
until monitoring of egg mortality identifies the presence or absence of a sensitive period.