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Efficacy of hydrogen peroxide versus formalin treatments to control mortality associated with saprolegniasis on lake trout eggs

Rach, J. J., Redman, S., Bast, D., and Gaikowski, M. P., 2005, Efficacy of hydrogen peroxide versus formalin treatments to control mortality associated with saprolegniasis on lake trout eggs: North American Journal of Aquaculture, v. 67, p. 148-154

Abstract

We compared the efficacy of hydrogen peroxide with formalin treatments to control fungal infections on lake trout Salvelinus namaycush eggs incubated at the Iron River National Fish Hatchery (Iron River, Wisconsin). Four strains of lake trout eggs were incubated in six vertical-flow Heath incubators; three replicate incubators for each chemical. Each incubator had 13 trays, and there was approximately 25,000 to 30,000 eggs per tray. Formalin (1,667 mg/L) or hydrogen peroxide (1,000 mg/L) treatments were administered once daily for 15 min up to the development of visible eye spots in the eggs (eyed egg stage). Eyed and dead eggs were separated using a photoelectric egg sorter and the number of live and dead eggs was determined volumetrically. In the hydrogen peroxide test group, the bottom trays of each incubator had fungus present on the eggs, while no fungus was observed on eggs treated with formalin. The mean percent of eyed eggs for an incubator treated with formalin (75%) was significantly greater (P < 0.05) than an incubator treated with hydrogen peroxide (70%). Formalin was the most efficacious therapeutant, however, both therapeutants were effective in increasing lake trout egg survival up to the eyed egg stage.

Keywords

Lake trout Salvelinus namaycush, hydrogen peroxide, formalin, saprolegniasis, Iron River National Fish Hatchery,