Alcalase enzyme treatment for elimination of egg stickiness in tench, Tinca tinca L.

Enzyme treatment to eliminate egg stickiness in tench was compared with standard methodology in an attempt to increase egg hatching rate under hatchery conditions. Three minutes after activation, eggs were exposed to an alcalase enzyme solution for 2 min. The highest hatching rate of 87.1% was found with 10.0 ml 1(-1) enzyme treatment. Batching rates of ca. 85% were recorded at 15.0 and 5.0 ml 1(-1), but hatching rate decreased to 80% at 20.0 ml 1(-1) enzyme. The traditional desticking procedure involving milk/clay treatment gave a hatching rate of 74.1% and required 1 h. Under fish farm conditions, the highest hatching rate of 88.1% was also recorded following treatment of eggs with 10 ml 1(-1) enzyme, while enzyme concentrations of 7.5 and 5.0 ml 1(-1) gave hatching rates of ca. 83%. Treatment with milk/clay solution gave a hatching rate of 30%. ANOVA showed significant differences between enzyme and milk/clay treatments on the hatching rate (P < 0.0001). (C) 2000 Elsevier Science B.V. All rights reserved.