Odd Man Out, Do Fish Have Personalities?

This Scientist Magazine article discusses the theory and recent research related to the existence of “personalities” and/or certain behavioral patterns in fish and other animals.

Personality may account for why individual animals behave differently in the same environment. However, historically researchers assumed that an individual’s behavior followed the rules of maximum fitness in any situation, changing its behavior according to the circumstances. The use of the word “personality” for species such as fish and spiders is controversial, even among scientists, but individual differences in behavior are a distinct phenomenon, whether or not they are termed “personality.”

It is this variability among individual animals regardless of circumstances that suggests that personality may come into play. A study conducted by Felicity Huntingford in 1976 found that stickleback fish who didn’t shy away from predators were also more aggressive with members of their own species, implying that some fish behave more aggressively than others not because of their circumstances, but just because they are more aggressive. Subsequent studies also suggested that different personality types seemed to be affected differently by certain pressures depending on the circumstances.

Animal personality researchers claim to have observed meaningful and consistent individual differences among a variety of organisms, including hermit crabs, squirrels, sheep, spiders, and lizards. But classifying these differences as personality remains controversial. For these studies to progress, theoretical models must be developed to explain how or why individual differences might have evolved.