THE mix of neurotic and outgoing characters in the hit children's movie Finding Nemo might be closer to real life than anyone could have guessed, research from a scientist at the University of Technology, Sydney, shows.

The biologist Peter Biro says fish have personalities, which can have a strong bearing on whether they fall prey to fishermen or other predators. Bold, confident fish are more likely to take risks to get food, while their shy compatriots escape the net or hook.

"We accept freely that there are shy and bold individuals among humans but we don't seem to want to believe that it happens in animal populations," Biro said.

He studied rainbow trout in a small lake in his native Canada, where he simulated a commercial Gillnet fishing operation on a small scale. "I was able to identify really distinctly that there were some very shy individuals in the population and some very bold individuals … Bold and active individuals tend to be faster growing in a population."

But these fishy daredevils only go to prove the rock'n'roll adage about living fast and dying young. "If you are zooming around the environment gathering food, there are lots of benefits but there is a big cost of making yourself visible to predators," Biro said.

His work has implications for fisheries. If bold fish get caught at a greater rate, there is a risk of "an evolutionary shift towards slower-growing, shyer individuals".