Communications: Clinical Evaluation of Formalin, Hydrogen Peroxide, and Sodium Chloride for the Treatment ofSaprolegnia parasiticaon Fall Chinook Salmon Eggs

Abstract

Abstract The effectiveness of formalin, hydrogen peroxide, and salt (NaCI) in controlling fungal infections on eggs of fall chinook salmon (Oncorhynchus tshawytscha) was evaluated under hatchery conditions. The clinical trial involved the treatment of eggs exposed to Saprolegnia parasitica with daily 15-min treatments of either 500 ppm or 1,000 ppm formalin, 500 ppm or 1,000 ppm hydrogen peroxide, and 15,000 ppm or 30,000 ppm salt (NaCI) solutions. Formalin and hydrogen peroxide at concentrations of either 500 ppm and 1,000 ppm appeared effective in controlling fungal infections on eggs. Salt solution at a concentration of 15,000 ppm failed to effectively control fungal infections. Although salt solution at a concentration of 30,000 ppm controlled fungal infection, the large quantity of salt required to treat eggs over the 35-d incubation period, coupled with an apparent increase in egg mortality, may render 30,000 ppm salt impractical for current hatchery operations. Both hydrogen peroxide and formalin a...