Personality Matters for Fish During a Fight

Just like a good underdog movie, the ability of a fish to win a fight depends on the level of aggression and the strength of personality, rather than the size of the fish.

The study was conducted by researchers from University of Exeter and Texas A&M University. In the study, researchers placed sheepshead swordtail fish (Xiphophorus birchmanni) in pairs in a fish tank. Researchers then recorded the fishes fight over a food source. The feeding contest trials included both male and female fishes. Study showed that males regularly fought for food, while females were less aggressive and rarely attacked other fish for food.

"We wondered if we were witnessing a form of Napoleon, or small man, syndrome. 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," said Dr. Alastair Wilson from Biosciences at the University of Exeter, according to a news release.

The study is published in the journal Behavioral Ecology and Sociobiology.

Personality in animals is considered to be a behavior that's frequently repeated. Previous research has suggested that some aspects of personality can be inherited from parents and play an important role in the growth and reproduction of animals.

There is also evidence that certain man-made products are wrecking the personality of fish. One study from Sweden pointed out that the mind-altering drug Oxazepam made European perch (Perca fluviatilis) isolated and aggressive. Also, exposure to birth control pills are wreaking the sex life of some fish by making the male fish less masculine and creating a condition called as intersex.