Thirty wild individuals of tench,Tinca tinca of Xinjiang population of China and thirty individuals of tench of Czech population,which were introduced into China in 1999,were collected in 2002.The isozymes of ADH,IDH,LDH,SDH,SOD,EST,MDH,ME,6PGDH,G3PDH and Muscle protein in their livers,muscles and other tissues were analyzed by using polyacrylamidae gel electroporesis.The loci of EST-2,SOD,ADH and IDH in Xinjiang population and loci of EST-1,ADH and IDH in Czech population were found to be polymorphic.The percentages of polymorphic loci of Xinjiang population and Czech population were 28.57% and 21.43% respectively,the mean heterozygosity were 0.0619 and 0.0357 respectively.It was found that there were some losses of heterozygosity in Czech population.Therefore,from the view of the genetic conservations,it was suggested that it should be forbidden to extend culture of tench of Czech population in Xinjiang Eltrix River basin.