Iodophor disinfection of eggs of spotted halibut Verasper variegatus and red sea bream Pagrus major

The suitable egg developmental stage and effective iodophor (Povidon-iodide) concentration for disinfection of spotted halibut Verusper variegatus and red sea bream Pagrus major were investigated. In spotted halibut, the suitable egg stage was the beginning of heartbeat, a day before hatching. The eggs were disinfected successfully by treatment with seawater containing iodophor at 75 ppm active iodide for 15 minutes. The hatching rate was decreased at higher concentrations. In red sea bream, the morula stage was most suitable for the treatment. The most successful concentration for disinfection was 100-200 ppm active iodide applied for five minutes. Furthermore, in spotted halibut, iodophor treatment did not have any harmful influence on survival, growth and occurrence of deformity. In the case of red sea bream, when eggs were obtained from the early spawning period, iodophor treatment seemed to reduce the survival rate of the larvae at an early stage, presumably due to egg quality. Growth and occurrence of deformity were not affected. The results suggest that the conditions for disinfection shown above are suitable for seed production. Moreover, the optimum conditions for iodophor disinfection of eggs differed between these two species. It is suggested that conditions for disinfection of eggs should be determined separately for each fish species.