DNA quality is an important molecular parameter that reflects the integrity of an organism’s genetic material. Nile tilapia (Oreochromis niloticus) is a high-value aquaculture commodity distributed through various marketing channels, including traditional markets and modern supermarkets. Differences in postharvest handling practices, storage conditions, and hygiene standards may influence the biological quality of fish, although these factors were not directly evaluated in this study. This study aimed to compare the DNA quality of Nile tilapia liver tissue obtained from traditional markets and supermarkets through DNA isolation using the meBEP kit, measurement of DNA concentration and purity with a NanoDrop spectrophotometer, DNA amplification by PCR, and visualization using agarose gel electrophoresis. NanoDrop measurements showed that samples from the traditional market (N1) had higher DNA concentrations (50.8–56.8 ng/µL) than samples from the supermarket (N2), which ranged from 3.1 to 6.1 ng/µL. The A260/A280 ratio of group N1 was more stable and closer to the expected range for pure DNA (1.63–1.66) than that of group N2 (0.78–1.54). However, all samples exhibited A260/A230 ratios well below the ideal value, indicating the presence of non-protein contaminants in the DNA isolates. Agarose gel electrophoresis showed no visible DNA bands for either the isolated DNA or the PCR products in both sample groups. These results indicate that, under the isolation and amplification conditions used in this study, the extracted DNA was of insufficient quality to serve as a reliable PCR template. The observed differences between sample groups should therefore be interpreted descriptively, as postharvest factors such as distribution time and storage temperature were not measured.