Fish can do Math

Christina Sng for Maths@Singapore

Yes, you read that headline right. Fish can do math.

In a study published in the journal Scientific Reports, researchers from the University of Bonn in Germany found that cichlids and stingrays could perform basic math functions with the numbers one to five. 

Maggie Parkhill of CTV News in Canada reports:

“In order to communicate with the fish, researchers showed the fish a certain number of geometric shapes in different colours…the researchers used these colours to teach the fish that the colour blue meant that they should add one, and the colour yellow meant that they should subtract one.

…the fish would be shown four blue squares. Then, after they had time to take in the four squares, they would be shown two new pictures – the correct answer depicting five blue squares, and one depicting an incorrect answer.

When the fish swam to the correct answer, they received food to reward them for associating the colour blue with adding one. The exercise was repeated with the colour yellow, which signalled to the fish to subtract one.”

“… the animals had to recognize the number of objects depicted and at the same time infer the calculation rule from their color,” Dr. Vera Schluessel, the lead author on the study, said. 

“They had to keep both in working memory when the original picture was exchanged for the two result pictures. And they had to decide on the correct result afterwards. Overall, it’s a feat that requires complex thinking skills.”

This came as a surprise to the researchers as cichlids and stingrays do not have a cerebral cortex, responsible for similar cognitive tasks in mammals. 

It is an exciting discovery that makes us wonder what else fish are capable of and contemplate how complex brains really are.

For the full report, visit

Thanks to Arthur Goldstein @atakalaka for making this photo available freely on Unsplash 🎁