Researchers at the University of New South Wales in Sydney have said that a slight increase in water temperature of just one or two degrees Celsius may cause some fish to become up to 30 times more active and aggressive.
Scientists believe that as the water becomes warmer, the animals' metabolism rapidly speeds up. Fish are ectotherms and their body temperature is the same as the environment around them.
There are concerns that as the world's oceans heat up under the effects of climate change, then bolder, more active fish may increasingly become targets for predators.
Dr. Peter Biro, from the University of New South Wales School of Biological, Earth and Environmental Sciences, explains this theory.
"If you are an individual fish swimming around the environment and you are active all the time, you are going to be visible and encounter predators more than an individual that is inactive, right, and so these activity level differences and boldness level differences in relation to temperature are going to have effects on risk to predation," he said. "And as a result of the warmer water temperatures animals were more active and they were more bold in the face of predators and that essentially got them killed."
Biro said the idea that fish have personalities may seem surprising but that such knowledge is important to help scientists understanding how animals respond to ecological challenges.
It is unknown what the long-effects of climate change may have on fish populations, although the team at the University of New South Wales believes that certain species could well adapt to warmer conditions.
Problems, however, could occur if the warming of the oceans fluctuates erratically, which would make it more difficult for marine animals to acclimatise.
The research was conducted on damsel fish, which are small, brightly coloured specimens that inhabit Australia's Great Barrier Reef.
Scientists have insisted the future of the world's largest coral system is threatened by pollution, global warming and rising levels of acidity in the ocean.
The reef stretches for more than 2,000 kilometers along the Australian continent's northeast coast and is home to a sparkling array of mollusks, fish, sea snakes and birds. The World Heritage Area attracts more than 2 million visitors every year.