Frightened Fish

Do fish show emotions? Rufus Wells of New Zealand’s University of Auckland says indeed they do. Writing in New Scientist, he says that “rather than regulating their cardiac output by varying heart rate like mammals, they change the stroke volume of their hearts.... The primary endocrine responses to stress in fish are a surge of catecholamines, followed by a sustained release of cortisol — precisely the same mechanism as in humans. The concentrations of adrenaline and cortisol that occur in fish exposed to such mild stresses as a person walking into the viewing gallery of an aquarium suggest that fishes are sensitive souls indeed.”

— From New Scientist, June 6, 1998