Buffalo fish , a type of freshwater fish native to North America, have a surprisingly long lifespan. They can live up to 100 years, and their health improves with age, according to a study published this month in Scientific Reports. Researchers used otoliths, small pebbles in their skulls, to determine their age, similar to the study of tree rings. The secret of their longevity lies in a unique lifestyle, characterized by calm waters, a balanced diet, and developed social interactions.