Banding techniques were carried out on metaphase chromosomes of zebrafish (Danio rerio) embryos. The karyotypes with the longest chromosomes consist of 12 metacentrics, 26 submetacentrics, and 12 subtelocentrics (2n = 50). All centromeres are C-band positive. Eight chromosomes have a pericentric C-band in each arm and 22 chromosomes have one in the longest arm. Two chromosomes have a slightly heterochromatic long arm and five chromosomes have an Ag-NOR at the terminal end of the long arm. Other banding patterns and sex chromosomes could not be revealed.