Fish appear to recognise themselves in mirrors

DARTING aimlessly around, they often appear… well, a little all at sea.

But don’t write fish off as fools, say researchers – because they can recognise themselves in mirrors.

A species of fish, the cleaner wrasse, has surprised researchers by fulfilling one of the primary tests of animal intelligence.

To see if they could recognise their reflection, scientists injected brown dye into their throats.

The species often cleans parasites off larger fish, and the idea was that they might mistake the dye for a parasite on their own body.

After looking in the mirror, the fish tried to remove the mark by scraping it against rocks in their tank.

When scientists at the Max Planck Institute of Ornithology presented them with an identically dyed fish, they stopped – suggesting they have some self-awareness.

Lead author Dr Alex Jordan said there was ‘little doubt’ fish pass the mirror test.

The study appears in the journal PLOS Biology.