Fish cell lines in aquaculture and biomedical research: A global perspective on development, repositories, and multidisciplinary applications.

Fish cell lines are indispensable in vitro systems that support diverse research areas, including virology, immunology, ecotoxicology, and biomedical science. Fish represent the most species-rich vertebrate group with remarkable genomic diversity, providing valuable resources for specialised cellular models. Since the establishment of the first fish cell line (RTG-2) in 1962, the global repository has expanded to approximately 918 authenticated cell lines derived from over 211 species. This review presents a comprehensive overview of the historical progression, global repositories, and current standards for cell line authentication. It summarises methodological advances in primary culture initiation, the development of continuous cell lines, and improvements in cryopreservation techniques. This review also critically explains the wide-ranging applications of fish cell lines in aquatic virology, vaccine development, and standardised ecotoxicological assays. The translational potential in biomedical research is also highlighted, particularly in cancer biology, regenerative medicine, and drug discovery, largely driven by the use of genetically tractable model species such as zebrafish (Danio rerio) and medaka (Oryzias latipes). Key challenges are also discussed, including mycoplasma contamination, cross-species misidentification, limitations in cryopreservation protocols for marine-derived cells, and the need for robust, open-access digital biobanking systems. Future perspectives encompass emerging technologies such as 3D organoids, organ-on-a-chip platforms, CRISPR-based genome editing, and serum-free culture systems. Integration of these innovations with omics approaches and adverse outcome pathway frameworks is expected to enhance the utility of fish cell lines, advancing research in aquaculture, environmental monitoring, and food security, while aligning with the principles of the 3Rs and the United Nations Sustainable Development Goals.