A study from scientists at James Cook University shows increased carbon dioxide levels impaired the senses of spiny damselfish, which live in the Great Barrier Reef.

Fish exposed to higher carbon dioxide levels - which are expected to increase in the oceans for several decades  - showed impaired cognitive function, learning difficulties, slowed visual capacity and altered sense of smell and sound.

But the possibility of fish behaving  badly is no laughing matter.

The damselfish also lose their ability to recognise threats, including the smells of predators when exposed to higher levels of carbon dioxide -  and will even become attracted to them instead.

Without the ability to sense danger, the fish are left much more vulnerable to predators, with potential flow-on effects up the food chain and the broader marine ecosystem.

The study's authors noted this was particularly problematic for juvenile fish, which are already vulnerable.

The negative effects of carbon dioxide on the damselfish appeared to be a result of interference with their neurotransmitters.

The study examined damselfish and their offspring in scenarios with different levels of carbon dioxide, including the higher levels predicted for the world's oceans in decades to come.

It tested their preference for swimming in water laced with "chemical alarm cue", and also recorded how often they swam left or right in a maze.

Alarm cues are chemicals released into the water when tissue is damaged, for instance when a fish is attacked by a predator.

Damselfish have a natural ability to sense danger by picking up on chemical cues.

Fish placed in high carbon dioxide levels chose to spend 80 per cent of their time in chemical alarm cue water, while the control group only spent 10 per cent of its time there.

Offspring that were not exposed to higher carbon dioxide, but whose parents were, also showed higher attraction to danger signals.

The fish showed no signs of adapting to higher carbon dioxide levels when exposed for weeks or months.

However the offspring of exposed fish did show some resistance to effects on metabolism, growth, danger-response and survival.