The memory span of fish is popularly deemed to be be only three seconds long, but British scientists believe they can prove fish are cleverer than their reputation suggests.
Researchers at the University of Bath and Queen Mary University of London say they have uncovered the first evidence that fish are able to process multiple objects at once.
Previous studies have suggested that fish did not possess "parallel visual search" as it had been identified only in primates, rats and pigeons.
In the study, published in the journal PLOS ONE, scientists studied 11 adult zebrafish, which they explained are genetically "surprisingly similar" to humans.
The fish 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 - surprising researchers by managing to quickly pick it out from a pile of other distracting discs.
Researchers believe that the greater insight into their mental sophistication could pave the way for medical advances, assisting stroke patients or those with attention deficit disorders.
Co-author Dr Matthew Parker, from Queen Mary University of London, added: "Fish don't deserve their reputation as the stupid branch of the animal family tree, the more research we do the more we find out that they are capable of quite complex learning and problem solving."