A lot more to fish like Nemo’s Dory than ‘just keep swimming’

Finding Nemo character Dory is not representative of her kind, according to a new study that proves fish are more intelligent than previously thought.

The popular Disney film depicts Dory as a typical fish, forgetting her surr-oundings and circumstances almost instantly due to a “three-second memory”.

That image could be a thing of the past thanks to scientists who have uncovered the first evidence that fish are able to process multiple objects at once.

Researchers say this proves fish are cleverer than their reputation and could pave the way for medical advances, assisting stroke patients or those with attention deficit disorders.

The University of Bath and Queen Mary University of London study is the first to identify parallel visual search, the ability to pick out one item in many, in zebrafish. Until this point, parallel visual search had only been identified in primates, rats, and pigeons, and scientists assumed fish did not possess it.

It was believed that, without the frontal part of the brain in the neocortex, fish have to examine each object individually rather than a whole scene together.

In the study, 11 adult zebrafish were presented with different coloured circles on a computer monitor over a six-day period to test their visual processing abilities.

The zebrafish were taught to associate food with a red disc and — to the delight of researchers — managed to quickly pick it out from a pile of other distracting discs. Dr Michael Proulx said: “Although vision seems simple and quick, it involves a lot of computational power to figure out where things are in a crowded environment.

“It is incredible to discover that the zebrafish brain, with its small size and simple structure, can seemingly find a target visually without getting slower.

“No matter how many items we added to the scene to distract the fish, they had no problem responding at the same speed every time.

“Now that we have discovered their mental sophistication, there is a great opportunity to discover the neural code and genetics of how humans pay attention, and apply those findings to treatments for those with ADHD or strokes.”

The paper, ‘Parallel Mechanisms For Visual Search In Zebrafish’, is published in the journal PLOS ONE.