Nucleic acids extraction is the initial stage of molecular genetic research. The effectiveness of using a certain method of DNA extraction is determined by the amount of extracted DNA, the degree of probe degradation, the time consuming and laboriousness of the procedure. When researching rare, endangered species and populations, special attention is paid to extracting DNA from sources that do not cause destruction or death of individual. The current study was aimed at comparison the effectiveness of the most common methods of genomic DNA isolation from fish tissues for further use in the polymerase chain reaction. Essentially three DNA extraction methods were employed and compared for the quality of isolated DNA ‒ the phenol-chloroform extraction method, the salt extraction method, and the sodium perchlorate extraction method. Samples of fins, liver and caver taken from sterlet individuals fixed in ethanol served as material for research. The study of the effect of DNA probe quality on PCR course was carried out using two types of PCR ‒ site-specific, amplifying the fragment of cytochrome-b gene, and multilocus ‒ ISSR-PCR with a trinucleotide primer (AGC)6T. A comparison of DNA extraction methods confirmed that all of them enable obtaining high-quality DNA from both fresh and archival fish tissue samples for site-specific amplification. The yield of nucleic acids using different fish tissues (fins, liver and caver) is not the same. Therefore, when it is necessary to obtain the maximum amount of DNA, it is advisable to use the salt extraction method. In case of ISSR-PCR, different degrees of DNA purification affected the course of amplification. Additional purification by the method of sorption on Silica allows removing possible PCR inhibitors and obtaining clear spectra of electrophoretic separation of amplification products, regardless of primary DNA quality.

Key words: DNA extraction methods, sterlet tissues, site-specific PCR, multilocus PCR.