Scientists at Concordia University in Montreal, Quebec, have been
studying the behavior of rainbow trout and the effects of certain
behaviors on survival. In an article in the journal Behavioral Ecology
and Sociobiology the researchers laid out how they divided the trout
into two groups -- those with bold behavior and those with what they
labeled as "shy" behavior.
The trout were sorted as to these behaviors when they were released from a confined pool by the removal of a Plexiglass barrier. The fish that left the pool first displayed more risk-taking behavior than those who took longer to leave. The fish had been conditioned to recognize the scent of a common predator. They were then tested to see how well they remembered the threat associated with that smell.
Those fish who demonstrated the bolder behavior were more likely to "forget" the threat, leaving them more open to predation. The shyer, more reserved fish showed that they retained the memory eight days later. This gives the shy trout the edge when it comes to survival.