Preventive efficacy of sodium hypochlorite against water mold infection on eggs of chum salmon Oncorhynchus keta

ABSTRACT:   To protect chum salmon eggs from water mold infection during incubation, the eggs were treated daily with sodium hypochlorite solution (NaOCl) at 10 mg/L residual chlorine concentration for 15 min during their developmental period from fertilization to eyed stages. The number of infected eggs and number of eyed eggs were observed on day 23 of incubation. The percentage of infected eggs to total eggs was significantly lower with NaOCl treatment (1.8 : 33.4%) than in the control (11.3 : 59.3%, P  < 0.01). The percentage of eyed eggs to total eggs was significantly higher with NaOCl (85.9 : 98.6%) than in the control (66.1 : 97.5%, P  < 0.01). The antifungal activity of NaOCl resulted in improving egg survival. Accordingly, NaOCl is a useful antifungal agent against water mold infection on chum salmon eggs.