Fish have complex individual personalities, a British university study found in research published Monday. Photo: National Geographic

LONDON: Fish have complex individual personalities, a British university study found in research published Monday.

Scientists from Exeter University in southwest England studied how individual Trinidadian guppy fish behaved in various stressful situations and discovered wide differences in how they responded.

The researchers studied their coping strategies in situations designed to trigger various levels of stress.

They found their modes of behaviour could not simply be explained as risk-taking or risk-averse.

"When placed into an unfamiliar environment, we found guppies have various strategies for coping with this stressful situation -- many attempt to hide, others try to escape, some explore cautiously," said Tom Houslay, of the university´s Centre for Ecology and Conservation.

"The differences between them were consistent over time and in different situations.

"So, while the behaviour of all the guppies changed depending on the situation -- for example, all becoming more cautious in more stressful situations -- the relative differences between individuals remained intact."

The tiny guppies were individually transferred to an unfamiliar tank, to create a mild level of stress, while a higher level of stress was caused by adding models of predatory birds or fish.

The study found that while introducing predators made the guppies overall more cautious, individuals still retained their distinct personalities.

"We are interested in why these various personalities exist, and the next phase of our research will look at the genetics underlying personality and associated traits," said Alastair Wilson, from the CEC.

"We want to know how personality relates to other facets of life, and to what extent this is driven by genetic -- rather than environmental -- influences.

"The goal is really gaining insight into evolutionary processes, how different behavioural strategies might persist as species evolve."

The paper, entitled "Testing the stability of behavioural coping style across stress contexts in the Trinidadian guppy", was published in the journal Functional Ecology.