For adult zebrafish, DNA was collected by swabbing. The collected material was placed in individual 1.5 mL plastic tubes. After removing the excess water, the tissue was incubated on ice for 5 min. Subsequently, 25 L of DNA extraction buffer (0.01 M TRIS-HCl, 0.05 M KCl, 0.3% NP40, 0.3% Tween 20, 1 mg/mL proteinase K) was added to each tube. The prepared samples were incubated at 55C for 35 h (until complete tissue digestion) with vortexing every hour. After tissue digestion, the tubes were placed at 95C for 15 min to inactivate proteinase K. The extracted DNA was purified using a DNA purification kit (Eurx, Poland) according to the manufacturers instructions.PCR primers encompassing the pygma and pygmb CRISPR sites (pygma Forward PCR primer 5-CACTTACCTGAACCAAAGACGA-3, pygma Reverse PCR primer 3-AACTCTGCTGTGTTCTGATCCA-5, pygmb Forward PCR primer 5AATTTTAATCGCCATCTGCACT-3, pygmb Reverse PCR primer 3-TATGTGAGTCGTGTTTTCGGAC-5) were used. The PCR product sequence was confirmed using commercial next-generation sequencing (NGS) analysis (Genomed, Warsaw, Poland) using AB 3730 Genetic Analyser (Applied Biosystems).