Abstract: During March to April in the year of 2015, we investigated and monitored the water quality changes of water treatment units in a closed recirculating nursery system for seed Cherax quadricarinatus Von Martens. The results showed that the values of TN, TP, NO₂-N, NO₃-N, NH₃-N and COD_Mn were low in headwater and conform to the aqua-cultural standard. The highest average values of TN, TP, NO₂-N and NO₃-N appeared in nursery pond, the values were 6.2, 0.76, 0.035, 4.2 mg/L respectively. The highest average value of NH₃-N was observed in the bagged filter（0.23 mg/L）. There was no significant difference in COD_Mn in all water treatment units. The values of water quality indicators were increasing with breeding progress proceeding. The water quality was becoming better after water proceeding in various water treatment units and ensured the process of nursery breeding.

Key words: recirculating system, Cherax quadricarinatus Von Martens, nursery, water treatment