Artificial incubation of noble crayfish (Astacus astacus) eggs in a partially recirculating system using formaldehyde as an antifungal treatment

There is little information on the long‐term artificial incubation of noble crayfish eggs. The present study evaluated artificial incubation in a partially recirculating system using formaldehyde baths as antifungal prophylaxis. Crayfish eggs were treated three times a week in a formaldehyde bath of 3000 ppm for 15 and 20 min and in 2500 ppm for 15, 20 and 25 min. In all treated groups, high final survival rates (87.8–92.0%) to stage 2 juveniles were obtained after 83 days. Significantly lower survival was observed in the control group (45.4%). It was concluded that recirculating systems can be used successfully for artificial incubation of crayfish eggs in order to conserve water. Formalin was found as an effective fungicide but its use should be carefully considered because of its safety issues for farm staff and environmental pollution.