The metaphase chromosome preparation of the fries PHA and colchicine injection. : The tonguefish Cynoglossus semilaevis (G?nther) bottom. metaphase chromosomes of one year old young fish which has physiologically sex differentiation has been got from their renal tissues by the method of The karyotypes were examined. The result shows that there are 42 acrocentric chromosomes in diploid and their karyotype formula is 2n = 42t , and there existed heterotypic sex chromosome which belongs to ZW/ ZZ type. The sex ratio in artificial bred stock is nearly 1∶1.