Fish can feel heartbreak too, say researchers

Monogamous fish experience heartbreak when they're separated from their other half, according to the CNRS, the French National Centre for Scientific Research in Dijon. Using a zebra Cichlid, a small fish that forms stable couples over time, researchers observed their reaction time to positive, negative and neutral signals when they are with their partner and when they are alone. The longer the reaction time, the worse the emotional state of the fish.