Turns out, it’s no joke. Just ask Christian Agrillo, a comparative psychologist at Italy’s University of Padova. In his research, Dr. Agrillo tests something called numerical competence. By placing three black dots in front of a desirable object (like food, or a door that leads to other fish) and two dots in front of an undesirable object (like no food, or a door that leads nowhere), Dr. Agrillo has been able to determine that fish have the ability to differentiate between different numbers.
Along the way, however, the researchers discovered something else. Put fish together and they make better decisions than they make when they’re alone.