Young Killifish Behavior Predicts How Long They Will Live

The way a young fish moves already says a lot about how long it will live. That is the finding of researchers who filmed killifish for their entire lives. These African fish live only about four to eight months, so a whole life can be watched. A computer program used nothing but the behavior of young fish to predict whether they would be short- or long-lived.

Cameras filmed 81 male fish in separate tanks, from sexual maturity until natural death. Fish that reached at least 200 days counted as long-lived. From 70 days of age, the prediction was right more than seven times out of ten. By 100 days, the fish that went on to live long were more active and swam faster. A behavior-based clock estimated each fish's age to within 12 days on average. Fish on a restricted diet looked 42 days younger than their real age by this clock.

Aging also did not unfold as a smooth decline. The fish moved through about six stable life stages, with sudden shifts between them. The authors note the exact number depends on how the model is set up. The main lifespan analyses used male fish, and a smaller group of females was also tracked. Whether any of this applies to people was not tested.