Fish behaviour affected by peers

Fish who display bold or shy personality traits are influenced by watching the behaviour of others, researchers have found.

Scientists at the University of Liverpool found some fish alter their behaviour according to what they observe in other fish.

The team found, for example, that bold fish become much more cautious after observing the behaviour of shy fish.

Dr Lynne Sneddon and Ashley Frost, from the university’s School of Biological Sciences, measured the responses of rainbow trout to various challenges.

They presented the fish with Lego bricks to elicit a fear response.

Bold fish approached the object within a few minutes, whereas shy fish took more than ten minutes to approach the object.

This allowed the team to distinguish which were the shy fish and which were the bold fish.

"We allowed the fish to interact for seven days and elicited social experience by raising an opaque partition in their tank for 15 minutes a day," said Dr Sneddon.

"Rainbow trout are a highly aggressive species and naturally form relationships of dominance in a very short time period.

"They chase after each other to try and exert their dominance."

Bold fish become shy

She explained: "We found the fish which attack the most and retreat the least demonstrated their enhanced status over others.

"Bold fish that lost their ‘battle’ became shyer than usual and shy fish who won their ‘battle’ became bolder.

"Equally, the more time bold and shy fish spent watching each other, the more their behaviour changed.

"Bold fish who observed the way shy fish reacted to the Lego objects became much more cautious in their behaviour.

"In contrast, shy fish who observed bold fish did not alter their behaviour - they remained just as shy as before."

The researchers believe that the shy fish observing bold fish decide their competitive ability as lower and so do not try to alter their behaviour.

Bold fish, however, adapt their behaviour to what others are doing and as a result of low social status.

Dr Sneddon added: "Personality types have also been observed in birds, mammals, reptiles and other fish.

"Personality type may be a strong driving force in the evolution of populations."

Dr Sneddon’s research is published by Proceedings of the Royal Society of London B.

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