Genotyping at 48 hpf for Early Identification of Mutant Zebrafish Embryos.

) is a commonly used model organism for human diseases due to its genetic similarities with humans since over 80% of genes associated with human diseases are also found in the zebrafish. For most genetic experiments, it is essential to gather tissue for genotyping in a nonlethal procedure. A common method is removing a part of the tail fin from individual adult zebrafish with a scalpel. The fin usually regenerates within 14 days, leaving the fish without permanent damage. However, larval genotyping might offer significant advantages, such as saving resources and reducing the number of research animals and enabling experiments on zebrafish embryos with a specific genotype. Here, we show a cost-efficient method for fin-clipping zebrafish embryos as early as 48 h postfertilization (hpf). When done correctly, the fin will regrow quickly, being nearly completely restored at 120 hpf. While the amount of extracted DNA is low, it is still sufficient for commonly used methods of genotyping. Embryos with the desired genotype can then be used for phenotypic or functional analyses or be raised to adulthood.