Researchers in Norway are developing new laboratory techniques that could improve understanding of fish diseases and genetic resistance while reducing the number of live fish used in experiments. The research may have important implications for salmonid producers, including trout farmers, as the industry continues to pursue better disease management, fish welfare, and production efficiency.
Infectious diseases remain a challenge for aquaculture, affecting fish survival, farm economics, and production sustainability. Researchers are also investigating how warming waters and other environmental changes may influence pathogen activity and the susceptibility of cold-water species.
For decades, fish-health and breeding programs have relied on challenge testing, in which live fish are deliberately exposed to pathogens under controlled conditions. These experiments help researchers understand disease progression, evaluate vaccines, and identify genetic traits associated with resistance. Such work has contributed to improvements in selective breeding and disease management, but it also raises questions about animal welfare and the number of fish required for testing.
Researchers are now exploring whether laboratory-grown fish cells can answer some of these questions without requiring comparable numbers of live animals.
Genetic Screening in the Laboratory
At Campus Ås in Norway, scientists from the Norwegian University of Life Sciences (NMBU), the Norwegian Veterinary Institute, and Nofima are developing cell-based methods to study fish genetics, disease resistance, and other production traits.
The PETRI-FISH project uses CRISPR-based genetic screening to generate large numbers of Atlantic salmon cells with different genetic changes. Scientists expose the cells to infectious viruses and examine which genetic variations are associated with better survival. Identifying these variations could help researchers pinpoint genes that may be useful in future selective breeding programs.
Another initiative, CELLCRISP, focuses on specific genes already suspected of influencing important traits. Researchers use different fish cell types to study characteristics such as disease resistance, growth, wound healing, fat deposition, and fillet quality.
These techniques could make it possible to evaluate promising genetic targets before proceeding to more resource-intensive studies involving live fish. They may also help researchers investigate biological questions that would otherwise require modifying fertilized eggs or conducting additional animal experiments.
Cell Models Could Support Broader Fish-Health Research
The Norwegian Veterinary Institute is developing specialized fish cell lines to investigate how fish respond to environmental conditions and disease-causing organisms.
One example is the ASG-10 gill epithelial cell model, which has been used to study Atlantic salmon gill responses to toxins, microplastics, water quality, and infectious agents. Gill health is particularly relevant to fish raised in aquatic production systems because gills play essential roles in respiration and the regulation of the fish’s internal environment.
More broadly, reliable cell models could provide researchers with controlled environments for investigating interactions between fish biology and pathogens. They may also help narrow the field of potential disease-resistance genes, making subsequent research and breeding investigations more targeted.
Developing these models requires careful validation. Researchers caution that cell lines must accurately represent the biological processes under investigation before they can reliably substitute for live-animal studies.
Reducing Animal Use Without Compromising Research
The work reflects the “3Rs” principles of animal research: Replace, Reduce, and Refine the use of animals in experiments. These principles encourage researchers to use non-animal methods where appropriate, minimize the number of animals involved, and improve experimental procedures to protect animal welfare.
Norway has been expanding its focus on alternatives to animal testing, including the establishment of a national 3R centre under the Norwegian Food Safety Authority. Research infrastructure is also being developed to advance fish-cell technology, genetic screening, and related approaches.
A proposed Blue Shield Centre of Excellence at Campus Ås would bring together specialists in fish genomics, immunology, virology, and disease development. This type of collaboration could help researchers better understand why some fish are more resistant to particular pathogens and how those findings might be applied in breeding programs.
Industry representatives have expressed support for these developments, recognizing the potential to generate useful genetic and biological information while reducing reliance on live-fish challenge tests.
What This Could Mean for Trout Producers
Although much of the current work focuses on Atlantic salmon, the underlying research approaches may be relevant to other cultured fish species, including trout. However, their applicability to trout will depend on developing suitable cell lines and validating the methods for the species and traits being studied.
For trout producers, advances in genetic screening and cell-based research could eventually support more targeted investigations into disease resistance and other commercially important characteristics. Better identification of genetic factors associated with resistance may help breeding programs develop more resilient stocks over time.
There are important limitations. Laboratory-grown cells cannot yet reproduce all the interactions among organs, immune responses, and other biological systems in a living fish. As a result, cell-based methods are expected to complement existing research initially, rather than eliminate live-fish testing altogether.
Continued cooperation between aquaculture producers, breeding companies, universities, and fish-health researchers will be essential to translating these technologies into practical applications.
The long-term opportunity is to develop more precise research tools that strengthen disease prevention and selective breeding while improving animal welfare. As these methods advance and are validated across species, they could become an increasingly valuable component of fish-health research and sustainable trout production.