Piscine Polemics: Small Tropical Fish Species as Models for Aging Research

Abstract The study of aging to date has focused on relatively few animal models, with round worms, flies, and rodents dominating the research landscape. Fish represent the largest class of vertebrates with longevities that span from months to centuries, yet little has been reported on the aging of any of these species. We review available information on several small tropical fish that have been used for gerontology research, including guppy, medaka, killifish, and zebrafish. Their longevities and aging characteristics have been described, and they have been used for studies on environmental manipulations that increase longevity including caloric restriction and temperature reduction, as well as to generate genetic models of accelerated aging. They have also served as valuable models for the emerging field of tissue regeneration and as an in vivo assay system for drug discovery research. Killifish has recently reemerged as an aging model promoted by its extremely short life span, though the species may be well suited for diapause and cancer research. Zebrafish have become a mainstay for nearly every biological discipline except gerontology. Driven largely by zebrafish biologists, the scientific tools and resources that are now available for several small tropical fish should allow them to better compete with invertebrates and rodents as models for aging research.