Document Type


Publication Date



Explaining consistent variation in the behaviour of individuals in terms of personality differences is one of the cornerstones of understanding human behaviour but is seldom discussed in behavioural ecology for fear of invoking anthropomorphism. Recently, however, interest has begun to focus on identifying personality traits in animals and examining their possible evolutionary consequences. One major axis used to define personality traits is the shyness–boldness continuum. We examined boldness in an in situ experiment using fish from eight populations of the poeciliid Brachyraphis episcopi (also referred to as Brachyrhaphis episcopi). Fish from high- and low-predation regions within four streams that run independently into the Panama Canal were tested. Boldness scores were strongly influenced by standard length and the relative level of predation pressure in the rivers. In all four rivers, fish from high-predation areas were bolder than those from low-predation areas. Fish became increasingly shy as they grew.


This file contains a post-print version of the article, which has the same content as the final edited version but is not formatted according to the layout of the published journal.