Karyotype of four mouth-brooding Betta fishes in Thailand

Abstract

The karyotype and chromosomal characteristics of nucleolar organizing regions (NORs) of four mouth-brooding Betta from Thailand: Betta pi, B. prima, B. pugnax, and B. simplex, were reported. The results exhibited that the diploid chromosome number (karyotype formula) and fundamental number (NF) of each species are; B. pi, 2n=34 (4m+4sm+18a+8t), NF=60, B. prima, 2n=38 (6m+12a+20t) NF=56, B. pugnax, 2n=40 (4m+2sm+14a+20t) NF=60, B. simplex, 2n=46 (2m+2sm+4a+38t) NF=54. All species revealed one pair of NOR-bearing chromosomes located on the short arm (p) of the acrocentric chromosome. In addition, the different sizes and morphology of Ag–NOR were observed in these four Betta fish.