CLOWNFISH can count to determine whether other fish are friends or foes, research suggests.
Experimenters discovered that they appear to recognize their own species from the number of stripes on their bodies.
The orange fish was portrayed as friendly in the 2003 animated Pixar film Finding Nemo.
But in reality, they are fierce creatures that aggressively defend their homes from rivals.
The researchers found common clownfish — which have three stripes — chased and groped their own kind and clownfish with two stripes.
But they didn’t mind those with a stripe or none.
Study leader Dr Kina Hayashi, of the Okinawa Institute of Science and Technology, Japan, said: “Common clownfish attack their own species quite often.”
He suggested that this may be related to their development.
The common clownfish initially develops two white stripes around 11 days of age, before acquiring a third three days later.
Dr Hayashi suspects that clownfish that grow up with other two-striped juveniles see similar competitors to drive away.
