Age-related diseases, such as kidney diseases, are becoming more prevalent in aging societies. Currently, patients with reduced kidney function require dialysis or organ transplants. Those who suffer from kidney disease would benefit from regenerative therapies. Thus, one of the ultimate goals of regeneration research is to enhance an individual's capacity of self-repairing damaged tissue; something that fish models can contribute towards. Kidney structures are conserved among vertebrates highlighting the opportunities for fish to act as human disease models. Here, different species can offer respective advantages. An understanding of the different modes of regeneration can help to visualize the differences in mammalian and fish regenerative capacity. The remarkable regenerative capacity of fish is well known, but kidney regeneration is an understudied area. The kinetics of kidney regeneration allows one to investigate early damage responses, as well as the initiation and completion of repair. Age-related reductions in regeneration are an additional societal problem; again an area where fish models can be of help. Age-matched experiments between varied vertebrate species will help us to learn from those that do or do not exhibit age-related phenotypes. The goal of such experiments is not only to outline important age-related factors and pathways, but, in addition, to see if age-related decreases in regenerative capacity can be reduced. Widening our knowledge of this very complex process will help to address many of the unanswered questions in the field.