As they swim gently around their tank or bowl, fish tend to enjoy a stress-free existence. But they face one great potential peril, scientists have found. Apparently, if they catch sight of their reflection gawping back at them, they try to fight it.
They are then terrified when their lookalike fights back in exactly the same way. Scientists say the discovery shows how similar their brains are to ours. Biologist Dr Julie Desjardins, who led the study, said: 'I think this indicates there is more going on cognitively than people have long assumed in fish.' Male African cichlids, a territorial species, were either shown their reflection or another fish behind a pane of glass. In both cases the fish tried to fight.
All showed high levels of testosterone and other aggression-inducing hormones in their blood. The fishes' brains were also examined but only those that had fought with their reflection showed high activity in the amygdala, the brain region tied to fear and fear conditioning in all vertebrates - including humans.
Dr Desjardins, of Stanford University, California, said the fear was due to the unfamiliarity of the encounter, adding: 'The fish was not seeing the expected response from its opponent. 'The fact we saw evidence of a really high level of activity in the amygdala is pretty exciting and surprising.'
Source: http://www.dailymail.co.uk/sciencetech/article-1280218/Are-looking-Why-fish-scared-reflection.html
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