A tiny fish that lives for just a few months is helping scientists unlock new insights into how kidneys age and how that process might be slowed, according to a new study published in the journal Kidney International.
Researchers studying the African turquoise killifish, one of the fastest-ageing vertebrates known, found that its kidneys develop age-related damage similar to what is seen in humans over decades. Because the fish completes its entire life cycle in four to six months, scientists can observe kidney ageing in real time, making it a powerful model for ageing research.
The study, led by an international team from the MDI Biological Laboratory, Hannover Medical School and Colby College, showed that as the fish aged, their kidneys lost small blood vessels, developed damage to filtration structures, showed higher inflammation and suffered disruptions in how cells produce energy. These are all hallmark features of kidney ageing and chronic kidney disease in people.
After establishing the fish as a reliable model, the researchers tested a class of widely used diabetes medicines known as SGLT2 inhibitors. These drugs are already prescribed to protect the heart and kidneys in people with and without diabetes, but the biological reasons behind their benefits are not fully understood.
The results were striking. Fish treated with SGLT2 inhibitors showed healthier kidneys as they aged. Their organs retained stronger networks of tiny blood vessels, more intact filtration barriers and better cellular energy balance compared to untreated fish. The treatment also reduced age-related inflammation and helped preserve communication between different kidney cell types.
Senior author Hermann Haller of the MDI Biological Laboratory said the findings help explain why the benefits of these drugs go beyond blood sugar control. He noted that the study offers biological evidence for why SGLT2 inhibitors consistently reduce kidney and heart complications across different patient groups.
One of the clearest differences was seen in blood vessel health. In untreated fish, ageing kidneys gradually lost capillaries, forcing cells to rely on inefficient backup energy systems. In contrast, treated fish maintained healthier vessels and showed gene activity patterns closer to those seen in younger animals, suggesting slower kidney ageing.
First author Anastasia Paulmann, who helped establish the killifish model, said the rapid-ageing fish allows researchers to compress decades of kidney decline into a short timeframe. This makes it possible to test therapies quickly while still generating insights that are relevant to human health.
The research team plans to study whether these drugs can also help repair kidneys after age-related damage has already occurred and whether the timing of treatment affects long-term outcomes. Scientists believe the fast-ageing fish kidney ageing model could speed up the search for treatments that help people maintain kidney health later in life.
The study was supported by funding from the US National Institutes of Health and several research foundations.
