A rapid chromosome preparation technique without metaphase arrest for ploidy determination in Nile tilapia, Oreochromis niloticus

Most chromosome preparation techniques use colchicine or colcemid in order to arrest cell division during metaphase, which usually involves the use of high cost materials. This research was aimed to simplify fish chromosome preparation technique without using colchicine or colcemid. Ten fish of different ages, namely one-, two- and three-month-old Nile tilapias, were used in this research. Tissues were collected on the caudal fin of the fish. Chromosome spreads was easily observed, using Giemsa or silver staining, five hours after the whole preparation process. The results showed that the one- and two-month-old fish had better mitotic index (0.008 and 0.01, respectively) compared to those of the three-month-old fish (0.005). This method is rapid, cost-efficient and applicable for ploidy level determination, and also keeps fish alive for subsequent evaluations.