In a startling study, scientists discover that clever fishes can add and subtract!

It is not just mammals and birds who can do simple addition and subtraction as studies have shown that bees and salamanders are capable of that. Now fresh research has added fishes – cichlids and stingrays – to that growing list as per a report in sciencealert.com.

Both the zebra mbuna cichlids or Pseudotropheus zebra and freshwater stingrays or Potamotrygon motoro have exhibited this capability which goes beyond symbol memorisation.

Sharing the essence of their study in a paper, Vera Schluessel and colleagues wrote: “Individuals did not just learn to pick the highest or lowest number presented based on the respective colour; instead, learning was specific to adding or subtracting 'one'.”

Schluessel is a zoologist at Bonn University.

Scientists showed the fish two gates which had cards with different number of shapes. On being shown a card that three blue squares, the correct door would have to be one with four blue squares, meaning that they have to add one and for this they will be rewarded. Likewise, when the shapes on the cards were yellow in colour, this translated into subtraction of one from the number of shapes to recognise the right door.

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