Small nest-holding male fish have more aggressive behavior than large ones, finds a new study.

A team of international researchers led by Dr. Andreas Svensson of Linnaeus University in Sweden in collaboration with Monash University and the University of Turku, Finland, studied the aggressive mating behavior of male desert goby fish.

They found that the small fish species in central Australia behave more aggressively than the large ones in order to protect their eggs from predator attacks.

According to the researchers, male goby fish are very protective of their nests. They can survive even in extreme environmental conditions. They are very small fish which grow around 2.3 inches (6cm in length). Females release around 250 eggs during mating, which the males guard until they are hatched.

Males defend their nests from any intruder attack, and fan the eggs using pectoral fins in order to allow water circulation that helps in getting oxygen for the eggs.

Experts were surprised to notice that the small male goby fish were more aggressive to protect their eggs. While they could not relate the behavior to the presence of females and male intruders, the researchers found that the aggressive nature was related to their size.

They suggested that the males might possibly indulge in such behavior as a strategy to attack the predator first in order to avoid showing their inferiority to the intruder and to prevent from getting injured by a far more superior attacker.

"We found the aggression of males was not affected by the presence of females and perceived mating opportunities or larger male intruders. Instead their aggression was related to their size.

"In particular, smaller males attacked sooner and with greater intensity compared to larger males, suggesting that nesting desert goby males used routine, rather than conditional, strategies for initiating aggression," Dr. Bob Wong, a Senior Lecturer at Monash University's School of Biological Sciences, said in a statement.

Experts pointed out that the male goby fish attacks the opponent first in the hope that the intruder would not strike back and leave.

Such aggressive males have been dubbed as 'the Napoleon complex,' after the French general Napoleon Bonaparte who possessed an aggressive personality.

The findings of the study are published in the journal PLoS ONE.