We evaluated bronopol as a practical alternative anti-fungal agent to malachite green for use in hatcheries. Repeated exposure everyday, just after fertilization to the stage of eggs showing eye development to 50 mg/L and 100 mg/L bronopol for 30 min showed an efficacy comparable to 0 mg/L (control) for the inhibition of fungal infection in rainbow trout (Oncorhynchus mykiss) eggs. The 100 mg/L bronopol treatment groups showed a control of fungal infection up to the stage of eye development in eggs. Significant differences in terms of the number of eggs showing eye development were seen between 0 mg/L and treatment at 50 and 100 mg/L bronopol.