Regeneration in fish, with special focus on killifishes

Killifish are notable for their remarkable regenerative capabilities, offering valuable insights into vertebrate tissue repair. This review synthesizes current knowledge on fish regeneration, focusing on the emerging model organism killifish Aphaniops hormuzensis (family Aphaniidae), a species capable of regenerating multiple structures-including the caudal fin, kidneys, central nervous system (telencephalon and spinal cord), and integumentary structures (scales). A comparative analysis with established models like zebrafish and medaka underscores the exceptional speed and efficiency of A. hormuzensis regeneration; it achieves complete spinal cord restoration within five days and brain tissue repair within seven days post-injury-significantly faster than zebrafish. The species employs blastema-mediated epimorphic regeneration, mirroring mechanisms in other teleosts but at an accelerated rate. Like many short-lived vertebrates, A. hormuzensis displays age-dependent declines in regenerative capacity, a trait explored in related killifishes. We explore the ecological and evolutionary implications of these traits, synthesizing how killifish models bridge comparative biology and regenerative medicine. The review critically evaluates the potential of killifishes, particularly A. hormuzensis, as powerful models for biomedical research, arguing that their unique regenerative kinetics and life history traits provide novel insights into neuroregeneration, organ repair, and the impact of aging on tissue repair. By highlighting these advances, this work underscores the importance of diversifying model organisms to fully understand the principles of tissue regeneration and their applications for human health.