July 15, 2024

# Science: plus and minus are not a problem: fish can count

Studies show: rays and perches solve positive and minus tasks. But what is the use of that for them?

Fish can count. At least in the range of numbers from 1 to 5 they can add and subtract “1,” as experiments with tilapia and rays have shown. The researchers, led by Vera Schlussel of the University of Bonn in Scientific Reports.

Some time ago, it was found that honeybees can add and subtract using a system of colored symbols. Scientists led by Key have now conducted similar experiments with Malawian blue tilapia (Pseudotropheus zebra) and peacock-eyed stingray (Potamotrygon motoro): the rays swam in a pool and a card with a certain number of colored symbols appeared in each experiment. Blue indicates “add 1”, and yellow means “subtract 1”.

### How do you know if a fish can count?

The animals then had to swim through an opening and then into one of two separate areas at the back of the pond to receive a reward. The two areas were marked with another card that showed either the correct or wrong solution to the arithmetic problem described earlier. So, if the fish first sees 2 symbols in blue (“Add 1”), it must swim to the area marked with 3 symbols. A card with two or four symbols indicates an incorrect solution. With tilapia, the experimental setup was different, but the principle was the same.

The scientists reported that six of the eight cichlids and three of the eight rays studied learned to correctly associate the colors blue and yellow with the associated mathematical tasks. So tilapia learned to calculate faster than rays, and a larger part of the tilapia group could perform the calculations. On the other hand, single rays in the calculation performed better than individual tilapia, so they correctly solved more tasks. Basically, the fish found addition tasks easier than subtraction tasks.

Overall, the tilapia was correct in 296 attempts out of 381—a 78 percent hit rate. Radiology got a score of 94 percent (169 out of 180 correct assignments). When subtracted, tilapia had an infection rate of 69 percent and rays of 89 percent.

### So why are there still “primitive” or “inferior” animal species?

Through the tests, the researchers ruled out that the fish simply chose the slots with more or fewer symbols, but actually added or subtracted exactly “1”. They also examined and ruled out the potential impact of token size on computing power.

The results are surprising, the researchers wrote, in that fish have no direct survival benefit from being able to calculate, at least that’s unknown. There may be previously unknown behaviors that depend on such computational abilities. However, the fact that not all fish can be counted indicates that ability is not particularly important for animals. It may be useful under certain conditions, but its absence is not a disadvantage either.

Rather, it is doubtful, given the abilities demonstrated, that there is still talk of “primitive” or “inferior” animal species. It is clear that a large and organized brain is not necessary for solving complex cognitive tasks. “It seems clear that fish, their cognitive abilities, and their place as a sentient animal urgently need to be reconsidered, particularly in light of the harmful human threats fish face on a daily basis.”