Fighting Fish: Aggression More Likely than Size to Win a Battle

When it comes to the wild, we certainly think that survival of the fittest always rings true. But does that always mean that the bigger, greedier animals take the cake? Not necessarily, according to a recent study by scientists at the University of Exeter and Texas A&M University. In fact, for fish, size may not matter so much at all.

The findings from the study actually suggest that when resources are in short supply, personality traits such as aggression could play a more important strength than size when it comes to survival.

Lead researcher Dr. Alastair Wilson from Biosciences at the University of Exeter found the findings to be quite interesting. "We wondered if we were witnessing a form of Napoleon, or small man, syndrome," Wilson said, according to a press release. "

"Certainly our study indicates that small fish with an aggressive personality are capable of defeating their larger, more passive counterparts when it comes to fights over food. The research suggests that personality can have far reaching implications for life and survival."

The sheepshead swordtail fish (Xiphophorus birchmanni) fish were placed in pairs in a fish tank, food was added and their behaviour was captured on film. The feeding contest trials were carried out with both male and female fish. The researchers found that while males regularly attacked their opponent to win the food, females were much less aggressive and rarely attacked.

As an animal's personality can be classified as behavior that is repeatedly observed under certain conditions, major aspects of personality, including shyness or aggressiveness, may have been previously characterized as important to ecological science. These traits may have, in fact, been seen as signs as of weakness or strengths. This study, indeed, highlights some of those beliefs.

The findings for the study were published in the journal Behavioral Ecology and Sociobiology.