Fish have unique, complex personalities

Sept. 25 (UPI) -- When researchers subjected Trinidadian guppies to a variety of social and survival scenarios, they found individual fish responded in unique ways.

The findings -- detailed this week in the journal Functional Ecology -- suggest fish have complex personalities.

Some scientists have previously argued that a fish's personality can been plotted on a basic spectrum measuring how risk-averse or risk-prone an individual is, but the latest research suggests a fish's disposition isn't so simply characterized.

"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, and so on," Tom Houslay, a researcher at the University of Exeter's Center for Ecology and Conservation, said in a news release.

Houslay and his colleagues induced mild stress by transferring a fish into an unfamiliar tank. Researchers upped the fear factor by adding 3D models of predators birds and fish to the tank.

Despite a diversity of responses to a variety of scenarios, the tests showed personality differences remained constant.

"While the behavior 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," Houslay said.

Researchers hope further testing will help them understand how and why personality differences develop and are maintained as a species evolves.

"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, a professor at Exeter and 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."