Activity levels and daytime sleepiness can be combined into a ‘behavioural clock’ that predicts whether a fish will have a short life or a long one.

A new study found that subtle differences in an animal’s behavior by midlife can predict how long it is likely to live.

You’re staring at your aquarium. It’s late. Everything is quiet. And there’s your fish, floating calmly, fins moving slowly, eyes wide open. Are they... asleep? Or just zoning out? Fish don’t come ...