By Daily Mail Reporter
The male cichlids were terrified when their reflections made exactly the same moves as they did
Fish are more scared of themselves than a real opponent, a new study has revealed.
Tests showed that male cichlids try to fight themselves when they spot their reflection gawping back at them in a mirror.
They are then terrified when their lookalike makes the same moves and fights back in exactly the same way.
Scientists believe the research may actually show that the brains of fish are surprisingly similar to humans.
Biologist Dr Julie Desjardins, who led the study, said: 'I think this stimulus is so far outside their realm of experience that it results in this somewhat emotional response.
'It seems it is something they don't understand. But I think it indicates there is more going on cognitively than people have long assumed in fish.
'Perhaps it is similar to when you are a little kid and someone keeps repeating back to you what you've just said - that quickly becomes irritating and frustrating.'
During the tests male African cichlids, a freshwater territorial fish, were either shown their reflection or another fish behind a pain of glass.
In both cases the fish tried to fight the 'other' fish, resulting in 20-minute long sparring sessions.
Afterwards, the scientists tested blood samples for testosterone and other aggression-inducing hormones. All fish showed high levels of testosterone.
The fishes' brains were also examined but only those that fought with their reflection showed high activity in the amygdala, the brain region tied to fear and fear conditioning.
Dr Desjardins, of Stanford University, California, suggested the fear was due to the unfamiliarity of the encounter: She said: 'In normal fights, the fish bite at each other, one after the other.
'But when you are fighting with a mirror, your opponent is perfectly in time, so the fish was not seeing the expected sort of response from their opponent.
'The amygdala is a part of the brain that has been associated with fear and fear conditioning, not only in fish but across all vertebrates.
'The fact that we saw evidence of a really high level of activity in the amygdala is pretty exciting and surprising