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Researchers in Norway are developing laboratory-based methods that could help the aquaculture industry better understand infectious diseases while reducing the number of live fish used in research. The work comes as producers face ongoing challenges from disease outbreaks, changing environmental conditions, and increasing expectations for animal welfare.

Disease remains a significant concern for aquaculture operations worldwide. Outbreaks can lead to fish mortality, economic losses, and potential impacts on surrounding ecosystems and wild fish populations. As water temperatures and environmental conditions change, producers and researchers are also working to understand how emerging pathogens may affect farmed species.

A major focus of the Norwegian research is finding alternatives to traditional disease challenge testing. These tests deliberately expose live fish to pathogens to study disease progression, evaluate vaccines, and identify genetic traits associated with disease resistance. Such testing has contributed to improvements in fish health and selective breeding, but it also raises animal-welfare concerns.

Using Fish Cells to Study Disease Resistance

At Campus Ås, south of Oslo, researchers at the Norwegian University of Life Sciences (NMBU), the Norwegian Veterinary Institute, and Nofima are investigating ways to use cultured fish cells to answer questions traditionally studied through live-animal experiments.

One initiative, the PETRI-FISH project, uses CRISPR-based genetic screening to introduce genetic variation into Atlantic salmon cells grown in the laboratory. Researchers then expose these cells to infectious viruses to identify genetic changes associated with survival. The findings could help identify promising targets for selective breeding programs aimed at improving disease resistance.

A related initiative, CELLCRISP, uses gene-editing technology to investigate specific genes associated with traits such as growth, disease resistance, wound healing, fat deposition, and fillet quality. By studying selected genes in cell cultures, researchers hope to validate their importance without always having to modify fertilized fish eggs or sacrifice live fish.

The Norwegian Veterinary Institute is also developing and validating specialized cell lines. For example, its ASG-10 gill epithelial cell model has been used to study Atlantic salmon gill responses to toxins, microplastics, water-quality conditions, and infectious agents. Such models could support research into how fish respond to environmental stressors and pathogens.

A More Targeted Approach to Research

These efforts align with the established “3Rs” principles of animal research: Replace, Reduce, and Refine the use of animals in experiments. The principles aim to replace animal testing where scientifically possible, reduce the number of animals required, and refine procedures to minimize suffering.

Cell-based research could allow scientists to screen large numbers of genetic variations more efficiently and identify promising areas for further investigation before conducting live-fish studies. However, researchers emphasize that these laboratory models must be carefully validated to ensure they accurately represent relevant biological processes in living fish.

Additional infrastructure and collaboration will be important to expanding this work. Proposed initiatives at Campus Ås include the Blue Shield Centre of Excellence, which would bring together expertise in fish genomics, immunology, virology, and disease development. The goal is to improve understanding of interactions between fish genetics and pathogens while developing better tools for disease prevention and resistance.

Implications for Aquaculture

Industry representatives see considerable potential in these approaches. Researchers working with Norwegian salmon producers and breeding companies believe that advances in genomics, cell culture, and gene-editing technologies could eventually reduce the need for some types of live-fish challenge testing.

Nevertheless, cell cultures cannot yet reproduce the full complexity of an immune response or the interactions among organs and biological systems in a living fish. Live-fish studies therefore remain important for answering certain questions, and researchers anticipate a gradual reduction in their use rather than their immediate elimination.

For the broader aquaculture industry, these developments highlight the importance of continued investment in fish-health research, genetics, biotechnology, and collaboration between producers and research institutions. Improved understanding of disease resistance could support more effective breeding strategies, strengthen fish welfare, and help producers manage disease risks under changing environmental conditions.

As these methods mature, they may become valuable additions to the industry’s toolkit for improving fish health and supporting the long-term sustainability of aquaculture.