Karyotype And Erythrocyte Size of Spontaneous Tetraploidy And Triploidy In The Loach Misgurnus Anguillicaudatus

Abstract

Although the chromosome number of loach Misgurnus anguillicaudatus has been believed to be 2n —50, an occurrence of small number of tetraploid and triploid individuals has been reported. In the present study, tetraploid individuals with 100 chromosomes and triploids with 75 chromosomes were confirmed among loach specimens examined. Diameters of erythrocytes are associated with ploidy; specimens could be categorized into diploid, triploid and tetraploid on the basis of the measurement of erythrocyte. Among 242 specimens, 14 tetraploid and 10 triploid loach were found by observing chromosomes and/or measuring erythrocytes. High frequency of tetraploidy was noticed in specimens from a commercial dealer, no tetraploidy was observed among specimens from wild populations, and one example was found among specimens from a fish farmer. The occurrence of triploidy was not unusual in any of these specimens. © 1991, The Japanese Society of Fisheries Science. All rights reserved.