Iodophor disinfection of non-hardened Lota lota, Salmo trutta, and Thymallus thymallus eggs: Tolerance levels and iodine permeability

Disinfection of non-hardened Lota lota, Salmo trutta, and Thymallus thymallus eggs with iodophor solution was investigated. The following results were obtained: 5 min after fertilization, non-hardened eggs could be disinfected with ≤ 1% iodophor solution (≤ 135 mg/l active iodine) diluted in 0.75% NaCl without negative effects on the rate of eyed stage embryos, the rate of hatched larvae, and the rate of misshaped larvae. After iodophor disinfection, the percentile mass increase due to water hardening was initially suppressed but compensated during later phases of the hardening process. As investigated in L. lota and S. trutta, disinfection of non-hardened eggs in iodophor solution diluted in water had a higher toxicity on the percentage of eyed stage embryos than iodophor solution diluted in 0.75% NaCl. Measurement of egg internal iodine concentrations in S. trutta and Thmallus thymallus demonstrated that iodine entered the egg in < 5 min and that iodine was found in the eggs in comparable concentrations to the disinfection solution. There were no differences in the egg internal iodine concentrations when eggs were disinfected in iodophor solution diluted in 0.75% NaCl or in iodophor solution diluted in water.