**Cichlids and stingrays can do rudimentary addition and subtraction in the one to five range. This was shown in a recent research conducted by the University of Bonn and published in the journal Scientific Reports. It is unknown why the animals need their mathematical ability.**

Assume you have some coins on the table in front of you. If the number is tiny, you can determine how many there are immediately away. You don’t even need to count them; just a quick look would enough. In this regard, cichlids and stingrays are startlingly comparable to humans: they can identify minuscule numbers correctly – and likely without counting. They may be taught, for example, to discriminate between quantities of three and amounts of four.

This is something that has been known for a long time. However, a study team lead by Prof. Dr. Vera Schluessel of the University of Bonn’s Institute of Zoology has recently shown that both species can compute. “We taught the animals rudimentary additions and subtraction,” Schluessel says. “As a result, they had to add or subtract one from an original amount.”

**Blue denotes “add one,” whereas yellow denotes “subtract one.”**

But how can you get a cichlid to say “2+1” or “5-1”? The researchers employed an approach that has previously been utilized effectively by other research groups to examine bees’ arithmetic abilities: They showed the fish a variety of geometric forms, such as four squares. If these things were blue, it suggested “add one” for the next discrimination. Yellow, on the other hand, signified “take one away.”

Following the initial stimulus (e.g., four squares), the animals were given two new images, one with five squares and one with three squares. They were rewarded with food if they swam to the proper image (i.e. the five squares in the “blue” arithmetic exercise). If they supplied the incorrect response, they were sent home empty-handed. They eventually learnt to identify the blue hue with a one-point rise in the amount presented at the start, and the yellow number with a one-point drop.

Can the fish, however, apply this expertise to new tasks? Had they really grasped the mathematical formula behind the colors? “We purposefully removed several computations during training to test this,” Schluessel reveals. “3+1 and 3-1, to be exact. The animals saw these two activities for the first time after the learning period. Even in those examinations, they picked the right answer more than half of the time.” This was true even when students had to choose between four and five items after seeing a blue 3 – two outcomes that were both larger than the beginning number. In this situation, the fish picked four over five, suggesting that they had learnt the rule ‘always add or remove one’ rather than the rule ‘chose the highest (or smallest) number provided.’

**Without a cerebral cortex, computing is impossible**

This success astounded the researchers, particularly because the tasks were far more difficult in actuality than they had been represented. The fish were presented a mixture of diverse forms rather than items of the same shape (e.g., four squares). A “four,” for example, might be represented by a tiny and bigger circle, a square, and a triangle, or by three triangles of varying sizes and a square in another computation.

“As a result, the animals had to detect the number of things presented while also inferring the calculation method from their color,” Schluessel explains. “When the original photo was swapped for the two outcome pictures, they had to store both in working memory. And then they had to decide on the proper outcome. Overall, it is an achievement that requires advanced cognitive abilities.”

Some may find this odd since fish lack a neocortex, which is the region of the brain known as the “cerebral cortex” in humans and is responsible for sophisticated cognitive processes. Furthermore, neither species of fish is known to need exceptional arithmetic ability in the wild. Other animals may be concerned with the strip count of their sexual partners or the number of eggs in their clutches. “However, this is not known from stingrays and cichlids,” says the University of Bonn zoology expert.

She also views the findings as indication that humans have a tendency to underestimate other species, particularly those that do not belong to our immediate family or mammals in general. Furthermore, fish are not very attractive since they lack fuzzy hair or feathers. “As a result, they are fairly far in our favor – and of little concern while dying in the terrible procedures of the commercial fishing business,” Vera Schluessel explains.