In this study, rainbow trout (Oncorhynchus mykiss) eggs were treated with effective doses of  Daenensis thyme, Thymus daenensis (20, 10 and 5 mgL^-1) and Mentha, Mentha longifolia (10, 5 and 2.5 mgL^-1), during incubation period (20 days) until hatching for 30 minutes per every other day as constant flow bath treatment method. The mortality level in normal control (without any treatment) was significantly higher than other groups (p<0.05). Level of mortality in egg treated with Daenensis thyme at 20 mgL^-1(12.01±0.357%) was significantly lower than both normal control (33.35±0.889%) and Mentha groups until the eyed-egg stage (p<0.05). No significant different was seen between Mentha at 10 and 5 mgL^-1mortality untileyed-egg stage(p>0.05).  The highest hatching rate (78.36±0.340%)was recorded in Daenensis thyme at 20 mgL^-1concentrations compared to other groups except Malachite green (p<0.05). Eggs treated with Daenensis thyme and Mentha essence showed greater mean percentage of survival and hatching rates compared to the normal control (p<0.05). However, essential oil derived from Daenensis thyme at 20 mgL^-1 probably has the potential to be used as health control of rainbow trout eggs against fungal contamination.