Dynamic population breeding improves turquoise killifish husbandry

A breakthrough in the management of turquoise killifish populations has been achieved by scientists at the Leibniz Institute on Aging, Fritz Lipmann Institute (FLI) in Jena, Germany. The development of a novel breeding strategy aims to enhance the long-term sustainability and reliability of these fish in aging research. The turquoise killifish, scientifically known as Nothobranchius furzeri, originates from southeastern Africa and is uniquely adapted to extreme seasonal fluctuations in its environment. Native to temporary water bodies formed during the rainy season, which vanish during the dry season, the species has evolved to complete its entire life cycle, from hatching through reproduction to natural death, within a few months. This exceptionally short lifespan makes the turquoise killifish a vital model organism for studying aging processes that typically span years in other vertebrates. The fish’s ability to endure harsh conditions is further enhanced by its capacity to enter a state of diapause, a natural resting phase where embryos can remain viable inside the egg for several years. This adaptation allows them to wait until favorable conditions return before resuming development. However, once hatched, the fish experience rapid aging, making them ideal subjects for investigating biological mechanisms related to aging. Researchers have found that various aspects of human aging, including changes in the immune system, brain function, and reproductive capabilities, can be effectively modeled using this species. Maintaining stable and genetically diverse populations of turquoise killifish presents significant challenges due to their short generation time. Within just a few weeks, the fish progress from juvenile stages to sexual maturity, increasing the risks of inbreeding, genetic drift, and unintentional selective pressures. To overcome these obstacles, Dr. Beate Hoppe, who leads the Animal Facility Fish at the FLI, and her team devised a new approach called Dynamic Population Breeding (DPB). This innovative method integrates multiple hatching events with overlapping breeding-age groups from different generations. By leveraging the embryos' natural diapause capability, the researchers gained precise control over hatching schedules, reducing reliance on single, large-scale breeding efforts and enabling more adaptable colony management. The DPB strategy includes rigorous quality control measures aimed at maintaining stable populations and ensuring the production of healthy offspring. Studies revealed that the reproductive performance of the fish declines with age, but through consistent monitoring of breeding pairs and the deliberate selection of high-quality individuals, these effects can be minimized. Less effective breeders are identified early and removed from the breeding program, thereby preserving the overall health and genetic diversity of the population. According to Hoppe, modern colony management goes beyond merely caring for the animals, it serves as a foundational element for achieving reliable research outcomes and minimizing the number of laboratory animals required. An additional aspect explored in the research focused on the impact of embryonic development stages on offspring survival rates. Findings indicated that the survival probability of young fish is influenced not only by the hatching success rate but also by the specific timing of hatching. Those that emerged soon after reaching the hatch-ready stage demonstrated a higher likelihood of surviving compared to those that hatched later. This insight provides critical information for optimizing breeding protocols and improving the viability of future generations of turquoise killifish. With the implementation of the DPB method, the FLI researchers have established a more sustainable framework for managing turquoise killifish populations. Their work not only enhances the feasibility of conducting aging research using this model organism but also contributes to broader discussions around ethical animal care and resource efficiency in scientific experimentation. As the field of aging research continues to evolve, the insights gained from this study will likely influence how similar organisms are managed in laboratories worldwide.