Fish species are expected to shrink in size by up to 24% because of global warming, say scientists.
Researchers modelled the impact of rising temperatures on more than 600 species between 2001 and 2050.
Warmer waters could decrease ocean oxygen levels and significantly reduce fish body weight.
The scientists argue that failure to control greenhouse gas emissions will have a greater impact on marine ecosystems than previously thought.
Previous research has suggested that changing ocean temperatures would impact both the distribution and the reproductive abilities of many species of fish. This new work suggests that fish size would also be heavily impacted.
As ocean temperatures increase, so do the body temperatures of fish. But, according to lead author, Dr William Cheung, from the University of British Columbia, the level of oxygen in the water is key.
"Rising temperatures directly increase the metabolic rate of the fish's body function," he told BBC News.
"This leads to an increase in oxygen demand for normal body activities. So the fish will run out of oxygen for growth at a smaller body size."
Taking both the movements and the physiological impacts of rising temperatures together, the research team concludes that fish body size will shrink between 14% and 24%, with the largest decreases in the Indian and Atlantic oceans.
When compared with actual observations of fish sizes, the model seems to underestimate what's actually happening in the seas.
The authors point out a number of limiting factors in their study, including uncertainties in the predictions for the climate and the oceans. According to Dr Cheung, further research is required.
"Our study shows that climate change can lead to a substantial decrease in the maximum body weight of fish. We need to look more closely at the biological response in the future."
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