A loss of the natural fear of predators can be a huge problem for fish.
"What we have now also found in our study of fish behavior in this environment is that the fish become bolder and they venture further away from safe shelter, making them more vulnerable to predators," said Alistair Cheal, co-author of the research, which was supported by the Australian Institute of Marine Science.
And this won't just be happening at vents -- it's a threat to the entire ocean. Global warming could cause oceans to become 170% more acidic by the end of the century, according to a report released last year.
While this study focused on small fish only, the researchers expected the ramifications of the problem to reverberate up the food chain. The study reads:
"Continuous exposure does not reduce the effect of high CO2 on behaviour in natural reef habitat, and this could be a serious problem for fish communities in the future when ocean acidification becomes widespread as a result of continued uptake of anthropogenic CO2 emissions."