Chromosomal Studies on a Threatened Fish Cyprinion semiplotus (Teleostei: Cyprinidae) from Arunachal Pradesh

Cyprinion semiplotus (McClelland) (Fam: Cyprinidae), also known asAssamese Kingfish, is a minor carp that occurs naturally in the Hill Rivers of North East India. This species is recognized as threatened as its occurrence has declined considerably in the rivers of Arunachal Pradesh in recent times. Hence, the present study is undertaken to establish base chromosomal data for application in future conservation measures. Five live specimens were collected from a tributary of River Dikrong near Itanagar, Arunachal Pradesh. Samples were processed for chromosome preparation using a colchicine-KCl flame drying method (Khuda Bukhsh Manna 1976). The diploid chromosome number (2n) for C. semiplotus was ascertained to be 50. The karyotype consisted of 12 metacentric, 8 submetacentric, 8 subtelocentric, and 22 telocentric chromosomes with a fundamental armnumber (FN) 70. No sex chromosomes could be identified. This is the first report of a karyotype for Cyprinion semiplotus. The possible evolutionary significance of chromosome number is discussed.