Laboratory and Production Scale Disinfection of Salmonid Eggs with Hydrogen Peroxide

Disinfection tests were conducted on eggs from rainbow trout Oncorhynchus mykiss, cutthroat trout O. clarkii, and brown trout Salmo trutta to evaluate hydrogen peroxide (H2O2) as an egg disinfectant. A daily drip of 500 mg/L hydrogen peroxide for 35min on eyed brown trout eggs safely led to significantly reduced bacterial abundance relative to untreated controls, but abundance did not differ significantly from that in a formalin treatment (2,000 mg/L for 15 min). Using water-hardened cutthroat trout eggs, hydrogen peroxide concentrations of (1) 10 g/L for 2 min, (2) 10 g/L for 3 min, (3) 15 g/L for 2 min, and (4) 1,000 mg/L for 15 min were compared with two controls (untreated; 100 mg/L iodine). Bacteria were significantlymore abundant in the untreated eggs, but abundance did not significantly differ among chemical treatments. In another test, rainbow trout eggs treated the day before hatch with 15 g/L H2O2 for 2 min had significantly higher mortality than the controls. In production-scale tests, 10-15 g/L H2O2 for 2 min was safe for rainbow and cutthroat trout eggs and significantly reduced bacterial abundance relative to that in untreated eggs. Complete disinfection was not achievable with either iodine or hydrogen peroxide. Daily drip treatment with either formalin or hydrogen peroxide significantly reduced bacterial growth and is recommended.