One of the keys for an optimal Eurasian perch aquaculture broodstock management is being able to determine the sex of individuals. For Eurasian perch, compared to other methods of sex identification of fish and according to the 3R principle (Replacement, Reduction and Refinement), ultrasonography is a rapid, non-lethal, non-invasive and accurate method. During two successive experiments, we used ultrasound to identify the gender of two immature Eurasian perch broodstock. In the last experiment, females were identified with 98.9% accuracy (n =180) and males with 98.8% accuracy (n =92). This method can be very beneficial for perch fish farmers or aquaculture research.