About 60% of the young orange clownfish found their way home

It found that most of the orange clownfish - made famous by the Finding Nemo movie - and vagabond butterflyfish returned to the reef where they had first hatched.

"Marine fish lay very small eggs, and when they do, they are released into the water column," explained Professor Geoff Jones. "They develop into a really tiny little larvae that we think drift around in the water currents, sometimes for months. "The missing link in our understanding of coral reef fish has always been: where do the larvae go?"

Until now, finding this out has been extremely tricky - attaching tags to miniscule larvae is not an easy task.

The study took place on a small reef in Kimbe Bay

So what the researchers did was to collect adult female coral reef fish from a small 0.3 sq km reef in Kimbe Bay, Papua New Guinea, and inject them with a rare, stable barium isotope. The females pass this isotope to their developing offspring where it accumulates in their bones, giving the baby fish unique chemical signatures.

A few weeks later, the team returned to the reef and collected young fish to test them to see if they carried the "tag". "We found that 60% - well over half - were coming back to the small island reserve, which was an unexpected result," Professor Jones told the BBC.

The scientists are uncertain how the vividly coloured orange clownfish and vagabond butterflyfish perform this feat, but hope to find out with further research.

Although the study was carried out on only the two species, Professor Jones believes the finding may apply to other coral reef fish too. If this is the case, it could have consequences for marine conservation. It shows that small marine reserves in which it is forbidden to take fish are a good way to protect over-fished species, he said, because there should be enough juveniles returning to the area to sustain numbers over time.