Genome editing introduces innovative techniques, such as the clustered regularly interspaced palindromic repeats (CRISPR) paired with CRISPR-associated protein (Cas 9), which hold promise for speeding up sustainable genetic enhancements in fisheries and aquaculture. The CRISPR/Cas 9 system consists of four main elements: target DNA, the Cas 9 enzyme, the protospacer adjacent motif sequence, and the guide RNA (or single-guide RNA). Compared to other genetic editing tools, CRISPR/Cas 9 is more affordable, simpler, and more accurate, making it a viable option for breeding technology aimed at addressing significant challenges in fisheries and aquaculture. The characteristics of many aquaculture species—such as high fecundity, external fertilization, short generation time, established breeding methods, and effective larval rearing support its application for CRISPR/Cas 9 genome editing. Genome editing enhances the breeding process through precise modifications in specific genes, with a high likelihood that desirable changes will be transmitted to future generations, typically requiring 1–3 generations to establish a new breed. Moreover, CRISPR/Cas 9 enables the swift introduction of beneficial changes by directly disrupting genes, avoiding the introduction of foreign DNA that raises public safety concerns, unlike transgenesis. Despite its significant potential, the CRISPR/Cas 9 technology faces various technical hurdles, as well as regulatory and public skepticism regarding its application in fisheries and aquaculture breeding. Nonetheless, an exciting development arose when two CRISPR-edited fish species, red sea bream and tiger puffer, created by a start-up in Kyoto, received approval for market sale, along with FLT-01 Nile tilapia from AquaBounty, which is not classified under genetically modified organism regulations.