The Effect of freezing on hatching efficiency, growth and survival of Artemia urmiana after hydration and dehydration

The aim of this research is the study of the freezing effects at -20°C after hydration and dehydration on the hatching efficiency, survival percentage and growth of Artemia urmiana cysts. Experiments were carried out in four treatments. In the first treatment, hatching was done after one hydration and dehydration cycle with the standard method. In the second treatment, hatching was done after one hydration and dehydration cycle and then one week freezing at -20°C temperature. In third treatment, hatching was done after one hydration and dehydration cycle and then one month freezing at -20°C temperature. Standard hatching was done without any other treatment in the control group (fourth treatment). Results indicated the cyst hatching percentage increased by increasing freezing time (one-month freezing), even though hatching percentage was higher in control group. The most survival percentage was observed in the 11th day of third treatment. The highest growth was in 15 to the 25th day of third treatment (P